Sabtu, 30 April 2011

Ways to Check the Engine Block for Cracks

Ways to Check the Engine Block for Cracks

Cracks in blocks can be illusive and difficult to detect when they occur in areas that can't be seen or are so small they give no outward signs of poor engine performance. Used blocks from dismantling yards can be even more questionable when the buyer has no history of the part. Even the slightest cracks or pinholes can lead to engine overheating which, left untreated, can lead to engine failure.

Dry Magnetic Particle Test

    Dry magnetic particle testing uses a process where crack detection powder is spread over the block surface during the application of a magnetic field. A hand-held portable electromagnet generates the field required to run the current through the metal being tested. Porous metals, such as cast iron, work best for the magnetic particle test. As the magnetic field comes in contact with the metal and the powder is distributed over the metal surface, any crack or deformity will show itself as an irregular pattern, be it a "shadow" line that follows the crack, or a smudge or glob that indicates a small hole. The dry powder (cast iron dust) comes in different colors, which contrast with the block's darker appearance, making the flaw stand out.

Wet Magnetic Test

    Wet magnetic testing uses a magnetic powder that combines with a carrier agent. The combination of these two ingredients forms a liquid that can be sprayed from a bottle. The chemicals allow it to fluoresce under a black light, showing small details in the metal's surface. With the wet method, the liquid flows into cracks and most small holes. This process can be very messy and requires a complete block wash, before reassembly, since the carrier spray agent has oil in it. With either the dry or wet magnetic testing methods, passing the hand-held electromagnetic device several times over the suspect crack can verify that a crack exists rather than making one quick pass over it.

Dye Penetrant Test

    As its name implies, the dye penetrant test uses a dye with special penetrating abilities that can seep into cracks and the tiniest of pinholes, unlike the magnetic process that may miss the smallest pinholes. Some dyes can be seen under a black light, which heightens their sensitivity, but the surrounding area must be dark to do so. Dye penetrant can also be used on aluminum blocks and non-metallic materials. Once the dye has been spread over the block surface and allowed to dry then wiped off, a developer has to be applied to the surface to draw the dye out of hidden cracks and pinholes. Whether under a black light or with the naked eye, the crack becomes apparent, even when looking for the smallest flaws.

Pressure Testing

    With pressure testing, the block has to be sealed off with numerous plugs and cover plates for a leak-tight fit. An air hose supplies pressure to the inside of the block passages. The test can be performed in a tank, where bubbles can be seen, or it can be performed in dry conditions with a spray bottle filled with a mild soapy water solution. Pressure testing can find internal cracks that are otherwise hidden from view or undetected by other testing methods. It can also verify the integrity of crack repairs that have been made in heads and blocks to make sure they hold water.

Turbocharger Failure Indicators

Turbochargers are essentially air compressors, and can fail like any other mechanical component. While not mechanically complicated, the turbo forms an integral part of your engine's intake and exhaust system. This means that any type of turbo failure can have far-reaching effects on your engine and vehicle performance.

Power Loss

    Power loss is one sure sign of turbo failure, but it generally doesn't have to do with a loss in boost unless the turbo itself is leaking. Worn-out bearings increase the blades' resistance to rotation, which will increase the amount of time that the turbo takes to get up to speed. While top-end horsepower might not necessarily suffer, horsepower and torque at lower rpm will.

Burning Oil

    Turbo oil seals get subjected to enormous pressures from every angle. A leaking oil seal will send oil through the compressor side and into the engine, resulting in black smoke and a loss in power. If you suspect oil leakage, remove the turbo-to-engine boost tube and check the inside for oil residue.

Noise

    A badly worn turbo will often emit a chirping squeal or whine that sounds something like a worn-out belt, but doesn't rise directly with rpm, like a belt would. An experienced mechanic will recognize this as the sound of dry bearings. Bearings worn this badly will often manifest as severe power loss and possible oil smoke before the turbo seizes up completely.

How to Retrieve Fault Codes for the Mazda 626 Diesel

How to Retrieve Fault Codes for the Mazda 626 Diesel

Whether diesel- or gasoline-powered, a Mazda's fault codes can be accessed and diagnosed with a handheld scanner. This is the most reliable way to find out why the "Check engine" light has become active. Vehicles operate under a standardized On-Board Diagnostic coding system, but currently, there are two types of code available. For automobiles manufactured before 1996, the hardware needs to know OBD-I fault codes. Vehicles after 1996 need OBD-II, and most scanners are not reverse-compatible. An OBD-II scanner will not understand OBD-I trouble codes. So before buying any diagnostic equipment, know the manufacture year. Once that is settled, retrieving the codes is a fairly simple process.

Instructions

    1

    Open the driver's side door, and insert the Mazda's key into the ignition. Leave the vehicle off for the time being, but you will be returning to this key later.

    2

    Locate the Mazda's diagnostic port. This outlet is the entry point into your Mazda's diagnostic system, and you should be able to find it somewhere under the dashboard.

    3

    Connect the OBD-II scanner into the diagnostic port. To do this, you will use the cable attached to the scanner, which ends in a many-pinned plug. This plug should be easy to push into place. If the port resists, push firmly, but do not force it.

    4

    Turn the key in the Mazda's ignition and start the car.

    5

    Watch the codes appear on the scanner's screen. Many OBD-II scanners will not provide a definition, so you will likely have to write the reported fault code down and look it up. Using Google, Bing or any other search engine, you can find a decoder, such as "Engine Light Help (see Resources).

What Causes My 2002 Yukon's Engine to Make a Tapping Noise While Warming Up?

General Motors produces the Yukon. The Yukon comes with a variety of options, such as the XL package, Denali package, or four wheel drive. The 2002 Yukon has had recalls, such as structural, brake and lighting problems.

Tapping Noise

    If the Yukon makes a tapping noise after being started, most likely the engine lifters and valves are "sticking." Worn oil running through an engine will cause deposits and engine "sludge." The deposits cause the lifter passages and valves to stick while moving up and down, which produce the tapping noise.

Solution

    Add a quart of engine treatment to the Yukon's oil, regardless of the engine size. The engine treatment will help to break down the deposits and sludge. The deposits and sludge will be trapped in the oil filter or removed in the next oil change. The treatment will also lubricate the metal areas to reduce friction and wear.

Warnings

    The tapping noise could also indicate an oil pressure problem in the 2002 Yukon. If the engine has an oil leak it could cause severe damage or even ruin the engine. Consult an authorized GM mechanic if the Yukon has an oil pressure problem.

Jumat, 29 April 2011

How to Troubleshoot Ball Joints

How to Troubleshoot Ball Joints

The automotive ball joint uses a ball and socket arrangement almost identical to a human shoulder joint. Ball joints allows rotational play while keeping a tight joint between the steering joint and the control arm. The control arm allows vertical movement while the ball joint turns with the steering wheel. The lower ball has to support the entire weight of the front end while keeping the wheels on a true and straight track. The upper ball joint assists with keeping the correct wheel alignment, but carries a much lighter load. Troubleshooting the ball joints requires some special knowledge and few tools.

Instructions

    1

    Drive your vehicle to a parking lot or location that has speed bumps. Drive over the speed bumps slowly, listening for any type of clanking, clunking or squeaking noise. Vary the speed a little and turn the wheel while the vehicle lifts up on the crown of the bump. Try different combinations of rolling over the bump at different angles and swaying the steering wheel back and forth. Dry or worn ball joints will make metal-to-metal noises that always come from the front end suspension.

    2

    Place the vehicle in park or neutral with the emergency brake engaged. Open the hood. Disconnect the negative battery cable at its post. Raise the front of the vehicle with the floor jack and place one jack stand under the frame near each front wheel. Use a shop light to inspect the rubber boots on the upper and lower ball joints. The ball joints attach to the large triangular-shaped control arms. If the rubber boots appear flat or collapsed it means they have lost grease on the inside. The ball joints should be replaced.

    3

    Determine if the ball joints have indicator pins sticking out of their ball housing. Indicator ball joints have been introduced on certain models and makes of vehicles. Refer to your owner's manual to ascertain if this is true for your vehicle. Indicator pins wear when the ball wears inside the socket. The pin either has only a small portion sticking out or will not be visible at all.

    Visually inspect the bottom rivet or bolt fastening of the ball joints; they should not be broken or missing. Excessive slop and suspension misalignment results in missing or broken mount bolts or rivets.

    4

    Lift the vehicle with the floor jack and place one jack stand directly under the lower control arm. Make sure the wheel does not touch the ground or contact the frame. Set the dial indicator on the ground and adjust the dial arm to rest against the wheel rim at its lowest point. Rock the wheel by hand in and out to get the dial indicator reading for horizontal movement in the upper and lower ball joint. The reading should not exceed the manufacturer's specification. GM ball joints, for example, can not exceed 3.18 millimeters. A higher number indicates too much play and requires ball joint replacement.

Kamis, 28 April 2011

How do I Convert My Buick R-12 to R-134A?

How do I Convert My Buick R-12 to R-134A?

If your Buick was manufactured before 1995, the air conditioning system uses R-12 freon, which is now highly regulated by the Environmental Protection Agency. In addition, R-12 is extremely expensive because it is no longer produced. The most cost effective way to recharge your Buick's air conditioning system may be to retrofit it for R-134a freon and recharge the system with R-134a yourself.

Instructions

    1

    Have your local mechanic recommend someone in your area who is certified to recover the R-12 freon from your system. The certified facility will have special equipment to recover the remaining freon and will flush your Buick's system.

    2

    Under the hood of your Buick, find both of the service ports on the air conditioner system. Use R-134a retrofit ports. Tighten over the original R-12 ports using a torque wrench.

    3

    Turn on the ignition in your Buick and turn your air conditioner to the maximum "cool" setting.

    Pushing back the locking mechanism, connect the recharge hose to the pressure gauge and the can of R-134a freon. Open the valve on the freon. This will create a vacuum to empty the hose of air. Close the valve so the hose fills with freon gas.

    4

    Open the valve again, and the freon will begin flowing from the recharge hose into your Buick's air conditioner system. This may take several minutes. You will know the process is complete when the pressure gauge reaches 40 psi.

What Happens When the U Joint Doesn't Work Well?

A universal joint, often called a U-joint, connects the drive shaft to the differential on many vehicles. The design, based on the ancient concept of the gimbal, allows power to be transferred from the transmission to the wheels that drive the vehicle even when the suspension travels up and down over bumps and dips.

Symptoms of U-Joint Failure

    When a U-joint begins to fail, the first symptoms are generally a clunking noise when the vehicle is in gear and vibration that mirrors the vehicle's speed, not the engine speed. When you suspect a faulty universal joint, you can remove it and rotate it manually to check for roughness and obvious problems, but there is no way to tell if a U-joint is in good or bad condition just by looking at it.

Cause of U-Joint Failure

    The U-joint rotates around an X-shaped center. One input shaft is attached to two opposite points of the X, and an output shaft or plate is attached to the other two points of the X. Each tip of the X has a greased bearing, and these are the weak points of the U-joint. Over time, the grease leaks out or loses effectiveness. The bearings begin to wear out and tear up the interior of the metal X-shaped center, until eventually the U-joint fails.

U-Joint Replacement

    To replace the U-joint, support the vehicle on jack stands and unbolt the drive shaft from the transmission and differential. Make reference marks on both sides of the U-joint assembly so that you can assemble it in its original configuration. Remove the caps on the X-shaped center and push the X out of the yokes with a U-joint tool, which resembles a large C-clamp. Replace the U-joint by reversing the removal procedure.

Similarity to Constant Velocity Joints

    Most newer vehicles replace U-joints with constant velocity (CV) joints. CV joints are more forgiving of operation at sharp angles. They also, as the name suggests, turn a shaft at the same velocity regardless of the angle of operation, whereas U-joints show some variation in shaft speed at different angles. U-joints are stronger than CV joints, but less flexible in their application. CV joints also use simpler bearings than U-joints.

My 1991 Acura Integra Won't Start

There a number of things that could cause an Acura Integra to not start, though with modern cars the most common reason is a dead battery. However if a car has not been well maintained then there are more complex problems that may be responsible. Generally in a well-maintained care the problem will be in the electrical system where as an abused car will have mechanical problems preventing it from starting.

Instructions

    1

    Turn the key. If none of the dash board lights come on, the engine doesn't turn over (you will be able to hear it chugging), and the the headlights don't come on then there is a problem with the electrical system; most likely the battery.

    2

    Open the hood to inspect the battery. If there is a foam on the battery it is leaking acid and you need a professional car mechanic to fix it. If there is no battery acid leaking, you may have a loose connection, which you can fix by tapping the terminals with a rubber mallet, or even the heel of your shoe to make sure the terminals have a better connection with the cables. Try to turn on the car again after this, if the lights come one then the problem is not electrical. If the engine turns over but does not start then you have a dead battery which you will need to replace.

    3

    If the electrical system is functioning but the Integra still won't start, you may have a flooded engine. A flooded engine means the spark plugs are wet and cannot generate a spark. To dry the plugs you need to enable the Clear Flood mode: this is done by depressing the accelerator all the way to the floor while continually turning the ignition. This causes the motor to pump air instead of fuel through the cylinders and will dry off the spark plugs. After a few minutes take your foot off the accelerator and take the key out of the ignition. Then put the key back in the ignition and turn the engine on. If your car does not start after this you have mechanical problems and will require a mechanic to properly diagnose.

Rabu, 27 April 2011

Oldsmobile Alero Power Train Problems

The Oldsmobile Alero, a compact car available with either an automatic or a manual transmission, was manufactured from 1999 to 2004. Although Edmunds.com contends that the Alero is an affordable used-car option, the vehicle experiences multiple power train problems.

Automatic Transmission

    Oldsmobile technical service bulletins (TSBs) report that a faulty torque converter clutch (TCC) is a common automatic transmission power train problem. TSBs indicate that TCC failure may cause poor acceleration, failure to upshift, difficulty shifting gears and slippage.

Manual Transmission

    TSBs report that clutch problems are common with multiple Alero manual transmission models. Clutch issues are mainly experienced when attempting to shift gears. Gear shifting problems are often accompanied with "grinding" or "rattling" noises coming from the transmission.

Solution

    Prior to replacing a TCC, you can perform a software update on the Alero's powertrain control module, which is the electronic brain of the vehicle. If an update does not remedy the issue, a TCC replacement is necessary. Manual transmission shifting difficulty is a sign that the clutch master cylinder requires replacement.

1993 Honda Accord Engine Troubleshooting

1993 Honda Accord Engine Troubleshooting

Troubleshooting a 1993 Honda Accord's engine can be frustrating if you do not know exactly where to look. Sometimes, the check engine light will come on although there will be no visible or audible symptoms. There is a very general way to troubleshoot the engine. The Accord has an On-Board Diagnostic system, and you can make the vehicle perform a self-diagnostic. The OBD-I system records malfunctions as they occur, and the self-test procedure will give you a list of active problems.

Instructions

    1

    Locate two wire connectors beneath the Accord's dashboard. They should be hanging loose in the passenger's leg space and be easy to see. You should not have to remove a panel to access them. Join the connectors together with jumper wire.

    2

    Insert your key into the Accord's ignition and switch it to the "On" position but do not crank the engine.

    3

    Look at the Accord's instrument cluster. The check engine light will flash trouble codes at you. Count the flashes and write the numbers down. Honda codes are two-digit numbers. The first number will be long flashes, and the second number will be shorter flashes. For example, Honda OBD-I code 13 will be a single long flash followed by three shorter ones. There will be a pause between trouble codes.

    4

    Look up Honda's OBD-I flash codes. Honda's codes can be found online or in a repair manual specific to your 1993 Honda Accord. The manual will not only give you the flash code definitions but will tell you, in detail, how to repair your Accord.

Selasa, 26 April 2011

How to Troubleshoot a 6.5 Turbo Diesel Oil Pressure Switch

The oil pressure switch on a 6.5 diesel is a multifunction unit. When closed it provides power to the fuel transfer pump, sending a signal to either an idiot light or an oil-pressure gauge on the dash. Problems with the switch can cause the engine to quit or run poorly.

Instructions

    1

    Open the hood and locate the fuel filter. Remove the two bolts holding the assembly to the block, and move it to the side. Removing the fuel hoses is not necessary. Look underneath for the oil switch. It is a small unit with a two-wire connector; it is screwed into the engine block.

    2

    Spray the switch with some cleaner -- if it is oily or dirty -- and wipe clean with the rag. Gently separate the plastic wire-connector. Examine it for corrosion, dirt or loose wires. Clean and repair if necessary. Reattach to the switch.

    3

    Locate a good ground connection for the voltmeter. Turn on the ignition and determine the 12-volt power supply by back-probing the connector. If there is no reading on the meter, check the appropriate fuse to see if it is blown. This test ensures that power is reaching the switch.

    4

    Start the engine after determining the power supply to the switch. Back-probe the two leads on the switch, and verify that the switch is closing. Twelve volts are optimally entering and exiting the swich. If not, replace the switch.

Troubleshooting the Dodge Stratus 1995 2.5 V6 Engine

The 1995 Dodge Stratus' engine is large, and troubleshooting it can be very difficult if you do not know exactly what you are looking for. But there is a way to simplify the process. It is by no means a silver bullet, but it is a way of finding places to start the troubleshooting process. The 1995 Dodge Stratus is outfitted with an onboard diagnostic system. Unlike vehicles from the 1996 model year and after, you do not need a hand-held scanner. You can make the "Check engine" light tell you where potential problems lie.

Instructions

    1

    Climb behind the 1995 Dodge Stratus' steering wheel and place your key into the ignition. Turn the ignition in the following sequence: "On"-"Off"-"On"-"Off"-"On." The turns need to be completed within five seconds. If you get no response from the computer, try the sequence again.

    2

    Count how many times the 1995 Dodge Stratus flashes its "Check engine" light at you. It will be in a special code. Dodge's flash codes are two numbers. For example, flash code 37 will be represented by three flashes, a pause, and seven more flashes. If there is more than one code in the system, there will be a slightly longer pause between code sets. Write down all the codes you find.

    3

    Look up Chrysler's flash codes online (see References). Both Dodge and Jeep are part of Chrysler's family of vehicle brands, and so all three companies will use the same coding system. Once you have found and read the definitions, copy them next to the code numbers.

    4

    Open the 1995 Dodge Stratus' hood. Start at the top of the list and investigate each engine area that corresponds with a reported code. Cross out codes once you have ruled them out as potential causes of the problems you are experiencing. If you lack experience with automotive engines, consider driving the Stratus to a mechanic. The list you will have made will save you from paying the mechanic's diagnostic fees.

Why Does a Diesel Truck Throw Oil Through the Antifreeze Tank?

The coolant system in your diesel truck is much like what is used in a gasoline powered engine. Coolant is pumped through the engine block, cylinder heads and intake manifold and is then pumped to the heater core and radiator for cooling before it returns back to the engine. Coolant mixing with oil and vice-versa is never a good thing and you should find the cause and implement a repair before driving the vehicle further. Either way after the problem is corrected you will have to clean out the engine oil system and the coolant system to rid them of any contamination.

The Primary Problem

    The coolant system and oil system in your truck are both individually sealed and fluids should never come in contact with one another. There are many mating surfaces where both oil and coolant travel where a potential gasket failure could cause the two to mix. Oil in your coolant can ruin the water pump along with clogging the radiator and heater core causing poor heat to the passenger cabin and the potential for an overheated engine.

Oil Cooler

    Most diesel engines have an oil cooler that is built into the radiator and is used to help keep the engine within operating temperature. A crack to the radiator and/or oil cooler can cause the two to mix and the coolant system becomes contaminated with oil. Common thought would tell you to expect finding coolant in the oil as well, but in most cases the oil pressure is higher than the coolant pressure so the oil will push past the coolant and not allow coolant back through. You can replace the oil cooler and radiator but before you install the new set up, you will have to flush the entire cooling system so that the new radiator does not become contaminated.

Gaskets

    The primary place oil and coolant can mix is at the head gasket or intake manifold gasket, if the intake manifold is cooled. Once again the oil pressure will likely exceed that of the coolant so its not likely you will find much coolant in the oil, if at all. It is possible for the engine to burn coolant if the gasket leak is bad enough; the tale-tale sign being white smoke from the exhaust. It is of course possible for oil to enter the coolant on a cooled intake manifold, but its not as likely as a blown head gasket. If the oil cooler replacement doesnt solve the problem, you will need to tear down the engine anyway. Inspect the intake manifold gaskets before removing the head bolts unnecessarily.

Recent Service

    You may also want to consider the last time a serious engine repair was performed. If the head gaskets or intake manifold gaskets were recently replaced, it is possible the bolts were not torqued properly or in the right order. Improperly fastened head bolts or intake manifold bolts will deform the gasket and create leaks. If internal repairs have been performed you may want to take it back to the repair facility that performed the repair if this problem occurred after the repair.

How to Troubleshoot a 1991 Lincoln Town Car

The base model of the 1991 Lincoln Town Car was equipped with a 4.6-liter, eight-cylinder engine. The sedan included many standard features, including a driver-side front airbag, front split bench seats, cruise control, 15-inch wheels, selfleveling suspension, power windows, air conditioning, power door locks, antilock brakes and automatic climate control. Because there are so many parts and systems on the car, it can be tough to troubleshoot the vehicle. One of the best ways to find problems before they start is to look at manufacturer recalls.

Instructions

    1

    Inspect the lower control arm ball joints of the car's front suspension if the front wheels respond abnormally when you turn the steering wheel. Some of the vehicles produced in 1991 were manufactured with a one-piece control arm ball joint bearing that weakens over time and cracks. If the joint bearing cracks the ball and cap of the joint will separate and the control arm of the suspension will drop to the ground. Replace both lower control arm ball joints to resolve this problem.

    2

    Examine the hood latch assembly if the car's hood fails to open after the hood release handle is engaged. The latch assembly could randomly release at any time, even while you are driving the car. The entire hood latch assembly should be replaced to fix this issue.

    3

    Check the fuel lines of the Town Car if you see any fuel leaks underneath the car. It is possible that fuel lines located inside the engine compartment have come into contact with the steering column. This will result in gas leaking out from the fuel line and may start a fire if the fuel comes into contact with an ignition source. Try to reposition the fuel lines so that they don't come into contact with the steering column and the parts attached to it, including the universal joint. If the fuel lines are damaged, repair or replace them.

Senin, 25 April 2011

Signs That Your Wheel Bearings Need Replacing

Wheel bearings are highly engineered little devices that perform a very simple task under some very demanding conditions. The wheel bearing's primary function is to facilitate wheel rotation, something that even a stick and a donut could manage, but it must do so while coping with thousands of pounds in sideways force and countless impacts and vibrations. Bearing failure is, sadly, inevitable, but identifying the symptoms early can save your dollars or your life later.

Wear Progression

    Slight wheel bearing wear will begin as a whine or hum, particularly while turning the steering wheel hard enough to cause the car to lean. This humming will eventually become almost constant, progressing to a rumble while turning. Once the rumbling becomes constant, it'll progress to a deep growl and noticeable vibration while turning the wheel or hitting the brakes. The growl and the vibration will eventually become permanent, growing louder and more severe until you can't ignore it and something important falls off the car.

Mechanical Damage

    Allowing normal wear to progress will eventually cause some sort of severe mechanical damage, but so can sudden impacts like speed bumps, parking standards and large potholes. Grinding while turning is a subtly but noticeably different thing than standard wheel bearing growl -- it sounds something like a cinder-block being dragged across a big metal plate -- and indicates a dry and damaged bearing. If you hear a snapping, popping, clicking or clunk while turning, then you may have severe bearing problems. Wheel vibration or wobble is a sign that one of your front bearings is extremely damaged. If your wheel starts wobbling and you continue to drive the car, then make sure that your will is up to date.

What It Isn't

    Suspension and steering systems are very complex, and a number of other malfunctions can feel or sound like bearing failure. A constant hum or vibration signifies bearing failure if it intensifies while turning or braking, but solely speed-dependent humming and vibration is likely a tire or something in the drivetrain. Bear in mind though, that while the vibration itself might just be a bad tire, that tire will eventually hammer your bearings to powder and then you certainly will have a bearing problem. Wheel wobble might be a bad tire, misaligned suspension, malfunctioning steering system, bent chassis or loose lug nuts. A hard knock or clunk under acceleration or deceleration is normally a bad CV joint, as is a constant clicking while turning.

Finding the Bad Bearing

    Bearing noise can be hard to find; you know it's there, you just can't tell which wheel it's coming from. The solution is testing by weight transfer. The car's body reacts to changes in direction by leaning away from them, transferring its weight to the outside tires while turning, to the front tires while braking and to the rear tires while accelerating. This increased load is what puts strain on your bearings, allowing you to hear or feel the symptoms. So, find a big parking lot and drive around in a circle at about 35 mph; if the bearing noise gets louder, the bad bearing is on the outside of the turn (right side if you're going counterclockwise, left side if you're going clockwise). Next, accelerate hard in a straight line to 50 mph and hit your brakes hard enough that you feel the front of the car begin to nose-dive. If the bearing noise gets louder during acceleration, it's the rear; if it gets louder under braking, it's the front.

How to Test the Coil on a 1995 Blazer

The 1995 Chevrolet Blazer was equipped a 4.3-liter CPI V-6 engine. The ignition coil on the 1995 Blazer is located on the passenger side of the engine, just above the engine valve cover. The ignition coil includes a single coil tower and one female electrical connector with two blades. Testing the ignition coil on the 1995 Blazer can be done in three different ways to make sure the internal components are not shorted, and that both ends of the coil are working properly.

Instructions

    1

    Open the hood of the Blazer and set the hood prop. Disconnect the negative battery cable from the battery using a ratchet and a socket. Remove the single ignition wire from the ignition coil tower by pulling it and applying a twisting motion with your hand. Remove the electrical connector by hand.

    2

    Inspect the coil ignition tower and wire, and the electrical connector port and wire harness to make sure there is not a buildup of corrosion or carbon on either part. If buildup is present on any of the parts, spray all of the parts with dielectric cleaner. Allow at least five minutes for the cleaner to evaporate before proceeding to the coil testing procedures.

    3

    Turn the dial on the multimeter to ohms. Look at the ignition straight on, with the ignition coil tower at the top and the electrical connector below. Insert the red probe on the multimeter onto the left-hand electrical connector blade. Insert the black probe onto the ignition coil body, down near the mounting bracket. The measurement should be "OL" or infinite. If you get a steady reading from this measurement, replace the coil.

    4

    Place the black probe from the multimeter onto the right-hand electrical connector blade. This primary winding measurement should be between 0.2 and 0.5 ohms. If the measurement is not within these specifications, replace the ignition coil.

    5

    Apply the black probe from the multimeter directly onto the ignition coil tower. This secondary winding measurement should be between 5,000 and 25,000 ohms. If the measurement between these two posts is not within specifications, replace the coil.

    6

    Installation of the coil wires is the opposite of removal. Install the negative battery cable after you install the coil wires. Tighten the battery cable snug with a ratchet and socket.

How to Troubleshoot a 2001 Plymouth Neon

How to Troubleshoot a 2001 Plymouth Neon

The Neon was a compact sedan manufactured by Chrysler. It was promoted under both the Dodge and Plymouth brand names, and ceased production following the 2001 model year. In addition to basic troubleshooting techniques, it is recommended to inspect the evaporator, leak detection pump, power-steering pump and air conditioning compressor. According to independent automotive research websites, as well as NHTSA TSBs, these components in particular are trouble spots for the Neon.

Instructions

    1

    Inspect the evaporator for any evidence of mold or bacteria. This may also manifest as a musty smell emanating from the A/C vents. Thorough cleaning of the evaporator with disinfectant or cleanser should remedy the problem.

    2

    Examine the vacuum lines that connect to the leak detection pump if the "Check Engine" light is illuminated. Clear any debris or clogging from the lines, and reconnect any that have come loose. If the "Check Engine" light still remains illuminated, it may be necessary to replace the entire leak detection pump.

    3

    Examine the accessory drive belts for both the power steering pump and the A/C compressor. If either one has become delaminated, replacement of the belt will be necessary.

Cadillac Brake Pedal Movement

The brake pedal in your Cadillac is designed to move up and down smoothly. The brake pedal is sensitive to any irregularities in the brake system. Abnormal movement is an indicator that a problem exists.

Pulsation or Vibration

    Pulsation or vibration is when the pedal moves up and down at a fast pace while bringing the Cadillac to a stop. This movement means that the brake rotor has excessive run-out and needs to be resurfaced or replaced.

Fading

    Brake pedal fade is when the pedal slowly moves closer to the floor board as you hold it. There are three possible causes of this movement: Brake fluid is leaking slightly, the hydraulic system is starting to fail, or the brake pad lining has worn too thin.

No Resistance

    Having no resistance in the brake pedal means the pedal quickly goes straight to its lowest point. This is a sign of one of three major brake system failures: severe fluid leak, failed hydraulic component or no brake fluid.

Minggu, 24 April 2011

The Causes for Replacing a CV Joint

The Causes for Replacing a CV Joint

CV (constant velocity) joints are articulated connections between the spinning drive axles and wheel hubs on vehicles. A CV joint allows the wheel and tire assembly to fluctuate up and down with the suspension while the axle continuously turns. The CV joint is an engineering contradiction--it sustains tremendous stress under operation but can be quickly damaged if exposed to dirt or other contamination. Unfortunately, a damaged CV joint cannot be repaired; the CV joint assembly must be replaced.

Boot Contamination

    The CV boot is a ballooned rubber sleeve encasing the CV joint assembly. The boot seals the CV joint and prevents contamination (dirt, water or any type of lubrication solvent such as gasoline) from entering the CV joint. As the CV constantly rotates and articulates while in operation, the slightest grime or solvent can quickly grind away metal parts or wash away petroleum lubricants. Both problems can lead to CV joint failure.

Wear

    With increased mileage, the CV joint can wear and lose the ability to articulate through a full range of motion. The driver will notice noises from the wheels and also changes in handling. The CV joint can become stiff or loose with wear, depending on the affected parts. Also, as the CV joint wears, the connections can become loose as metal works on metal. Lubrication can reduce the metal wear, but eventually, the CV joint will reach its maximum lifespan. Whenever the CV joint is replaced as a result of increased wear, the CV boot should also be replaced. The boot is composed of rubber and will dry and lose flexibility with age, decreasing its ability to protect the new CV joint.

Lack of Lubrication

    The CV joint is lubricated with grease. A port permits a grease gun for injecting lubricant into the joint without removing the boot. If the CV joint goes for too long a period without lubrication, the available lubricant will break down with use, and the moving parts will generate friction and wear. Another complication is the lubrication can be contaminated with age. Even though the metal parts are lubricated to reduce friction, small particles of metal from the CV joint itself can become suspended in the lubrication. Eventually, these particles can work back into the moving parts and lead to wear despite adequate lubrication. A regular CV joint inspection can determine if the available lubricant should be removed, the components thoroughly cleaned and clean lubricant added.

What Would Cause a Whining Sound From the Power Steering Unit When Turning?

What Would Cause a Whining Sound From the Power Steering Unit When Turning?

Most drivers are familiar with power steering whine, but few know exactly what causes it. Steering whine is often an indicator of low fluid levels, but may also indicate a malfunctioning bypass valve, a pump on the way out or a malfunction in the power steering rack that causes a pressure buildup in the system. That being said, your vehicle is probably just low on fluid.

Power Steering Pump Basics

    A power steering pump works by using motion from the crankshaft to turn a pump wheel or rotor. As the rotor spins, it pulls fluid from the power steering pump reservoir and pushes it into a high-pressure chamber. This chamber has two outlets: One goes to the power steering rack, and the other is a bypass channel that goes back into the reservoir. A spring-loaded, one-way valve in the bypass channel opens when pressure in the output line exceeds a certain psi limit; that way, the pump can continue to move fluid, even though it isn't needed in the power steering rack.

Whining Causes

    The whining noise you hear coming from the power steering pump is one of three things. The first is more of a loud "hush" than a whine; this is the sound of fluid rushing through the bypass valve when you turn the wheel all the way to one side or the other. Sometimes the bypass valve malfunctions or doesn't open all the way, causing pressure to back up in the pump and cause your engine rpm to drop. The second and third causes result from cavitation -- vacuum pockets created behind the rotor's vane blades as a result of extremely high pump action -- or air in the lines.

The Nature of the Whine

    When the vacuum pockets collapse or the air bubbles break, they create a constant and miniature "sonic boom" on the line. This sonic boom imparts a harmonic vibration to the mechanism, causing the pump and lines to act like a big speaker diaphragm. When the metal components vibrate, they create an audible whine that increases with pump cavitation or the amount of air in the lines. The harder and faster you turn the wheel, the more pressure will build up in the pump and the more cavitation or oil foaming will contribute to whining.

The Problems

    While a certain amount of whine -- actually bypass noise -- is normal, excessive whine is usually the result of low power steering fluid levels. When levels drop low enough, the pump rotor will suck air into the oil mixture and create compressed bubbles. Bubble decompression and splitting creates whine. Whining may also result from a malfunctioning bypass valve that allows an excess of pressure buildup in the pressure chamber. Once pressure builds up past a certain point, the pump will fail to move fluid and go into cavitation. Low power steering fluid levels and cavitation both manifest as a whine that rises with steering effort, becoming more severe at the steering extremes when pressure in the chamber peaks.

Sabtu, 23 April 2011

Troubleshooting a 1986 Nissan Pickup Clutch

Troubleshooting a 1986 Nissan Pickup Clutch

The 1986 Nissan Pickup clutch allows the engine to be engaged and disengaged from the manual transmission and the rest of the drivetrain. It includes a clutch disc, pressure plate, flywheel and release bearing and is actuated through a hydraulic system attached to the clutch pedal. The clutch is located in between the engine and transmission and cannot be inspected or repaired without removing either the engine or transmission. Removing the transmission is the simpler choice of the two.

Instructions

Shift Lever will not Go in Reverse

    1

    Put the transmission in "Reverse" with the engine running. If it doesn't go into "Reverse" at all or not without grinding or pushing hard on the shifter, remove the transmission. There may be internal problems in the clutch or with the hydraulics. Something is keeping the clutch engaged if it won't go in reverse. Usually, either the clutch plates are frozen together or the hydraulic system is not able to push the two sides apart.

    2

    Inspect the clutch hydraulic system for problems. Check the fluid reservoir on the driver's side firewall in case the level has dropped. Fill to the line with brake fluid, pump the clutch a few times, and check again to see if the level has dropped again. This could indicate either a leak in the hydaulic lines or air in the lines that needs to be fixed.

    3

    Follow the hydraulic lines to the bell housing where they are attached to the slave cylinder. Look for signs of leakage. Use a wrench to remove and replace any section of broken line. Bleed the system by connecting a tube to the bleeder screw on the slave cylinder and dipping the end of the tube in a jar of clean brake fluid. Have someone depress the clutch all the way very quickly. Watch for bubbles in the jar. Keep the reservoir full and repeat the procedure until no air bubbles are visible in the jar. Close the bleeder screw, and remove the tube. If bleeding the hydraulic system and fixing breaks or loose connections does not help, it may be that the piston seal in the master cylinder is damaged and not sealing properly

    4

    Remove the transmission and inspect the clutch plates. They may be contaminated with oil and require replacement or cleaning with brake cleaning solution. Replace the clutch plates if they appear warped or damaged. Check the diaphragm spring for fatigue, and look for leaks in the hydraulic system inside the clutch assembly.

The Clutch Slips when Trying to Accelerate

    5

    Inspect the clutch plates for wear and contamination from brake fluid or oil. Replace any worn or contaminated clutch plates

    6

    Inspect the diaphragm spring, as it may be weak or damaged and need to be replaced. Other causes of slippage include a warped flywheel and debris that keeps the hydraulic piston from going back to its normal position.

    7

    Give your clutch a week or so to get broken in if you have just had new clutch plates installed. It takes between 30 and 40 starts with the clutch before the plates match perfectly.

Clutch Noise and Chatter

    8

    Inspect the clutch plates for oil or hydraulic fluid, and replace them if they have been contaminated.

    9

    Inspect the engine mounts. If they are worn or loose, they will cause the engine and drive train to rattle and shake as the clutch is engaged. Tighten or replace the mounts, if necessary.

    10

    Inspect the splines on the driveshaft just behind the transmission. If the splines are worn they will cause a clanking noise at startup and gear changes. Replace them if they are worn.

What Causes the Ignition Module to Go out in a 1985 Fiero?

The Pontiac Fiero was born in 1984 as a two-seater mid-engine coupe with lots of potential. Whether that potential was eventually realized or not, the addition of a V-6 engine option in 1985 was a step in the right direction. The high-energy ignition system of either the base four-banger, or the V-6, operated on the same basic principles, with similar components. Ignition module failure occurs abruptly, with a finality that provokes disbelief. Any car of this vintage may be prone to breakdowns, but certain design characteristics of the Fiero make the ignition module more susceptible to demise than similar modules with more conventional configurations.

Hot Bodies

    Cars with engines in the front benefit from cooling air passing through the engine compartment. Fiero radiators and cooling fans are mounted in front to take advantage of air flow, but the rearward engine compartment is left to swelter. The engine itself suffers no direct harm, thanks to the capable cooling system, but some of the underhood components are less fortunate. Electronics do not tolerate excess heat very well, and an ignition module is no exception. A generous application of heat-absorbing dielectric grease is recommended for the underside of all G.M. ignition modules of the day, but the greasy heat barrier is vital for any appreciable module service life in a Fiero.

Pick Up Lines

    A related ignition component that is subjected to the same torrid temperatures as the ignition module is the pick-up coil. The coil supplies the signal that the module uses to time ignition sparks at the plugs. As the name suggests, the pick-up coil consists of wire windings wrapped around an iron core. Electrical resistance in a coil can vary by ambient temperature, but one at either end of its specified range might go beyond limits in operation. Constant function at the edge of tolerances places a strain on the ignition module. The wire lines, or leads, that connect the coil to the module may also develop excess resistance after extended use in the extreme conditions. A pick-up coil that is less than ideal can ruin a new ignition module immediately, or after some very short-lived success.

The Last Dance

    Excess electrical resistance in secondary ignition circuits can cause residual energy to seek an unintended course to ground. Defective spark plugs, plug wires, or distributor caps can obscure the path normally traveled by the powerful energy, causing miniature lightning to dance about in the distributor cap. Carbon tracks trace the activity inside the distributor cap as a black powdery residue where the voltage takes repeated detours. The powdery traces can offer a path of least resistance for the electrical charges, which then ground out on the distributor body, or breaker plate. The ignition module is mounted to the breaker plate, and does not endure many such surges.

The Break Up

    Broken connections in ground circuits can cause intermittent problems to become a permanent source of frustration for a Fiero owner. A temporary loss of engine ground could cause the ignition module to fail, or disrupt other circuit operations. Oily and grimy engine surfaces can prevent isolated components from grounding completely. The base of the distributor, as well as engine ground straps, and wiring harness connectors, must be kept clean, tight, and dry to ensure connectivity. Harness connectors may suffer corrosion not visible to casual inspection, and should be disconnected, cleaned or repaired as needed. Dielectric grease should be used to seal some harness connectors, if the part manufacturer, or factory shop manual so recommends.

Jumat, 22 April 2011

What Is an Alternator Exciter?

What Is an Alternator Exciter?

An alternator is an auto part that transmits power from the fuel system to the battery for operating vehicle accessories, such as the radio, headlights and air conditioning fans. A wire called an exciter generates the voltage needed for an alternator to start working once a vehicle is started.

Description

    Generally, three wires are connected to an alternator, including the exciter wire. The exciter, which is a low-voltage generator that transmits DC power, sends electric current directly to the alternator.

Malfunction

    If the exciter wire is disconnected or not working properly, it will not transmit voltage to the alternator, and as a result, the alternator will not generate enough power to operate accessories. Initially, alternator failure may not cause any symptoms since a vehicle's battery has some reserve power, but eventually, the reserves are depleted and accessories like the radio and air conditioning will stop working.

Exceptions

    The alternators on most modern vehicles have internal voltage regulators; therefore, they don't need an exciter wire to function properly.

How to Troubleshoot the Fuel System on a 1991 Ford Ranger

How to Troubleshoot the Fuel System on a 1991 Ford Ranger

When your fuel system stops working correctly, it can cause plenty of problems. If your truck sputters or won't start, you may well need to troubleshoot the fuel system. Troubleshooting your 1991 Ford Ranger fuel system can be done right at home with just a few tools. Here are some ways that you can try to locate the issue with your fuel system.

Instructions

    1

    Park the Ranger and set the emergency brake. Open the hood.

    2

    Find the fuel line that is connected to the fuel injector unit. This is located on the top of the engine. You will know the fuel line because you can follow it under the car to the fuel tank.

    3

    Remove the fuel line from the injector unit. There may or may not be some fuel in the line, so be prepared to let it fall onto the rag.

    4

    Have your friend turn the key to the "On" position and see if fuel comes out of the fuel line. If fuel is coming out of the line, then your problem is most likely not the fuel system. If there is no fuel, then move on to the next step.

    5

    Have your friend turn off the ignition key. Follow the fuel line back until you find the fuel filter. The fuel filter is located under the truck in the fuel line. It will look like a larger cylinder attached to the fuel line. Remove the line on the front side of the fuel filter with the screwdriver set. This is the side closer to the front of the vehicle.

    6

    Have your friend turn the key on again. Notice if fuel starts to release from the fuel filter. If fuel is not flowing through the filter, then you could have an issue with the fuel pump or the filter. At this point you will want to remove the filter completely by using the screwdriver set to remove the other connection. Have your friend turn the key on again. If fuel does not come out of the line, then you will need to replace the fuel pump in the fuel tank. If fuel starts to flow, then you know the filter is the problem and you will need to replace it.

Kamis, 21 April 2011

A 2003 Trailblazer With Radio Problems

A 2003 Trailblazer With Radio Problems

A 2003 Chevrolet Trailblazer with radio problems is frustrating because it is difficult to determine what causes the problem. Technical service bulletins (TSB) and consumer reports show that most of the radio problems stem from electrical problems in the Trailblazer. The only radio problem which is not attributed to the electrical system is the compact disc (CD).

Onstar System

    The Onstar system on the 2003 Trailblazer may affect the operation of the radio and other electrical accessories. The radio may not operate because the Onstar system, which runs through the radio, is remaining in the "On" position. The radio speakers are used by the Onstar system like a receiver on the telephone. Since the speakers are open, the radio does not work.

Fuse Failure

    The 2003 Trailblazer has fuses located under the hood of the vehicle as well as smaller fuses under the dash. A 125-amperes (amp) fuse under the hood of the Trailblazer controls many of the interior accessories of the Trailblazer, including the radio. The fuse may blow when the vehicle is jump-started, affecting the radio operation.

Wiring Harness

    The wiring harness that is located under the dash of the 2003 Trailblazer can cause problems with radio operation. The main problem with this wiring harness is the connections. According to the TSB published by the manufacturer, the wrong size connection are installed on some Trailblazers. These connections do not provide enough voltage and amps to operate the radio.

Volume Featue

    A TSB published on the 2003 Trailblazer concerns the volume feature on the radio. The volume control may not work because the contacts inside the radio volume feature are not making contact. When the volume feature is pressed, the distance between the contact points is too large to make contact and this prevents the radio volume from being raised or lowered.The only correction for this radio problem in the Trailblazer is to have the radio repaired.

CD Player Failing

    Consumer reports on the 2003 Trailblazer concern the CD player on the radio. According to these reports, the CD player may not eject or accept CDs. No specific cause is attributed to this radio problem. The only correction for this radio problem is to replace the entire radio assembly.

Rabu, 20 April 2011

Blown Head Gasket Diagnosis

The head gasket forms a seal between the engine block and the cylinder head, and it must keep the engine oil, cooling fluid and combustion gases separate. Symptoms of a blown head gasket generally involve the undesired mixing of these fluids.

Oil and Coolant Leaks

    Examine the upper part of the engine for fluid leaks. A leaking head gasket will often reveal itself through oil or coolant leaks around the upper part of the engine where the cylinder head and the engine block meet.

Engine Oil Symptoms

    A light beige froth or foam in the engine oil is a sign that cooling fluid is leaking through the head gasket and mixing with the oil. This foam will usually be visible with the oil on the end of the dipstick.

Cooling Fluid Symptoms

    If engine oil is leaking through the head gasket and mixing with the cooling fluid, you will see an oily scum floating on the surface of the cooling fluid in the radiator, and the cooling fluid will have a brown, oily appearance.

Engine Exhaust Symptoms

    A blueish smoke in the engine exhaust is a sign that oil is leaking into the engine cylinders. A white smoke indicates that cooling fluid is leaking into the cylinders.

Jeep Wrangler Idle Problems

Jeep Wrangler Idle Problems

The Jeep Wrangler was initially developed by AMC as a replacement for the the Jeep CJ-5 and CJ-7. Four Jeep Wrangler models were manufactured by AMC and later by its acquisitor, Chrysler. Troubleshooting a rough-idling Jeep Wrangler is within the skill-set of the average home mechanic.

Carburetor Adjustments

    Check for misadjusted carburetors. Older Wrangler models came with one- and two-barrel carburetors. Clogged jets, or a stuck choke will cause the Jeep to idle roughly. Be sure to check that the fuel filter is not clogged.

Fuel Injectors

    Check the fuel injection system. On newer Jeeps with fuel injection, low fuel pressure, and clogged injectors cause rough idling and hesitation when driving.

Ignition Problems

    Fouled spark plug or cracked spark plug wires can cause idling issues. Check the timing of the engine to ensure the cylinders are firing in the proper order and sequence.

Vacuum Hoses

    Worn, damaged or cracked vacuum hoses prevent the engine from idling or running properly. Replace any of these hoses.

Selasa, 19 April 2011

Why Is There No Pressure in My Car's Cylinder Head?

Why Is There No Pressure in My Car's Cylinder Head?

Engines are basically big air pumps that suck oxygen in, combine it with fuel, squeeze it till it goes boom and then expel it. While engines can tolerate some failure or restriction in the sucking-in and blowing-out phases, a lack of cylinder pressure will end the whole party in a heartbeat.

Valves Open

    The most obvious and likely reason for a zero-pressure reading is that you have one or more valves hanging open. There are a lot of things that could cause the valves to hang open, failure to rotate the engine so that both valves on a cylinder are closed being chief amongst them. Other causes include worn valve guides, broken valve springs, damaged rocker arms and cam followers, stuck hydraulic lifters, broken valves, bent valve stems and broken timing chains or belts. The quickest way to check for a stuck valve is to remove the valve cover and rotate the engine to close both the intake and exhaust valves. When the rocker arms reach the top of their travel, you should be able to squeeze a thin feeler gauge in between the rocker arm and valve tip.

Blown Head Gasket

    Blown head gaskets are next up in terms of likelihood, as they're the primary sealing element between the head and block interface. Head gasket failures are likely on older engines, particularly those that have iron blocks and aluminum heads or have seen one or more overheating events. Iron and aluminum expand at different rates, and over time those minute shear forces on your head gasket may eventually cause the seal to break and the gasket to blow. Odds are good that you'll find some sort of fluid or gas crossover as an additional symptom. Common crossovers signs include white exhaust smoke, actually steam from water in the cylinder, blue exhaust smoke, oil in the chamber, water in your oil, oil in your water or fuel-scented bubbles in your radiator.

Head or Block Damage

    Head or block damage may be and probably is the root cause behind most blown head gaskets, and it's something to check into if you diagnose a blown gasket. A cracked head or block may cause you to loose cylinder pressure, but those cracks are usually so tiny that pressure will slowly bleed off instead of outright failing to build and reading zero on your compression gauge. Cylinder heads -- be they aluminum or iron -- are shot through with dozens of tiny holes and passages, and those change the head's expansion characteristics relative to the block. After overheating, the thinner and more delicate head will tend to warp and try to pull away from the thicker and sturdier block. This makes the head-mating surface wavy, which inevitably results in head gasket failure.

Piston Ring Seal

    Piston rings can malfunction in a number of ways, either by crack and breaking, or by rotating in their respective ring lands so that the ring gaps align and allow pressure to leak out. This last may be the case if the pistons have lost their protective coating, thus becoming thinner, if heat expansion in the piston itself has widened the gaps or if the rings lose tension in an excessively worn bore. That last is extremely likely for older engines, which will naturally lose ring tension as the bores wear and the rings lose their springiness.

Pistons

    If your valves are closing completely, your head gasket is fine and the rings are sealing, then the only remaining problems include major and extremely expensive mechanical failures. You may have cracked a piston. This is a distinct possibility if you have hypereutectic or high silicone content pistons -- and its almost a guarantee if you have them -- you have lost cylinder pressure and have used nitrous at some point. Prolonged detonation or knocking will also shatter HT pistons like glass, and will melt a hole in cast and forged pistons. At this point, you'd better hope that one of these is your culprit, because the only other possibilities include broken connecting rods or a snapped crankshaft.

Why Is My Car Headlight So Weak?

For better or for worse, headlights don't typically fail outright; they get gradually dimmer over time before failing completely. However, dim lights might or might not be the result of a failing bulb, particularly if you use certain types of projector headlights that won't dim before going out.

Bad Bulbs

    This is probably the case if one headlight is slightly dimmer than the other or if you've got old sealed-beam lights. Newer halogens, projector beams and xenon bulbs will generally dim slightly before blowing out, but most likely not enough to be noticeable to the average driver. Sealed-beam headlights will dim themselves practically out of existence, eventually going from a weak white to a sickly yellow before failing.

Bad Ground

    Headlights are one of the most amperage-hungry appliances on your car, which makes them far more sensitive to drops in current than most other systems. Loose, corroded and frayed ground wires will reduce current flow through your system as a whole, and will result in noticeable dimming in the headlights. Watch your instrument cluster; if it gets dimmer when you engage the bright headlights, then take a look at your battery terminal connections and the negative ground strap on your battery or engine, and clean them if necessary.

Worn Alternator

    A worn alternator will manifest most of the same symptoms as a bad ground, but headlight brightness will generally rise or fall in direct proportion to engine rpm. Of course, that depends on the exact fault in the alternator itself; a bad voltage regulator that provides consistently low voltage may continue to do so regardless of engine speed. Older vehicles often use an external voltage regulator, but newer units are built right into the alternator. The surest test is to use a digital multimeter or voltage meter to check power supply right at the lights' wiring harnesses.

Lens Damage

    Acrylic headlight covers may look snazzy from the factory, but they're much softer and more vulnerable to damage than the old glass lenses. As you drive down the road, dirt and dust particles constantly sandblast your headlight covers to a milky haze. This, combined with surface yellowing of the plastic will dim your headlights by diffusing the light instead of allowing it to project cleanly through, although this problem will generally apply to both headlights equally. Fortunately, the fix for this problem is pretty easy; a bit of plastic polish and a rag may help to shed some light on your diffusing dilemma.

Senin, 18 April 2011

How to Troubleshoot the Programming Key Fob for a 1994 Corvette

The remote keyless entry system for your 1994 Chevrolet Corvette consists of a transmitter, also known as a key fob, and an on-board receiver. When programmed correctly, the key fob will transmit commands to the vehicle's on-board receiver, which in turn will direct the receiver to unlock or lock the doors or rear hatch of the vehicle. If you are having issues programming the on-board receiver to work with a replacement or supplemental key fob, several troubleshooting methods may identify the problem.

Instructions

Transmitter Battery Replacement

    1

    Examine the rear of the transmitter and locate the small rectangular-shaped slot.

    2

    Insert a small flat-head screwdriver in the slot and pry the two halves of the transmitter apart.

    3

    Remove the old battery from the transmitter.

    4

    Insert the replacement battery into the battery holder; make sure the + side of the battery is facing up for proper installation.

    5

    Mate the two transmitter halves together, using your fingers.

Fuse Check

    6

    Open the passenger-side door and locate the fuse panel cover.

    7

    Turn the fuse panel knob clockwise or counterclockwise to open the panel cover.

    8

    Examine the fuse box and locate fuse labeled 26 P.K.E. Remove the fuse, using your fingers or an automotive fuse puller.

    9

    Inspect the fuse; make sure the small metal element between the plastic housing of the fuse is intact. Insert a replacement 5A fuse into the fuse holder if necessary.

    10

    Inspect the 20A fuse labeled 42 POWER LOCK in the same manner; replace the fuse if necessary.

Proper Programming Procedure

    11

    Remove the transmitter from your keyring. Set the transmitter at least 15 feet away from the vehicle.

    12

    Insert the ignition key into the ignition. Switch the ignition to the ON position.

    13

    Hit the TRIP/ODO button two times. Press and hold the FUEL INFO button within five seconds of pressing the TRIP/ODO button.

    14

    Release the FUEL INFO button when the REMOTE KEYLESS ENTRY instrument cluster light turns on. Switch the ignition key to the OFF position; do not remove the key. After switching off the ignition, the REMOTE KEYLESS ENTRY light will begin to rapidly flash.

    15

    Exit the vehicle and retrieve the transmitter.

    16

    Walk toward the driver's side of the vehicle, and make sure the REMOTE KEYLESS ENTRY light stops flashing and turns solid. Walk away from the vehicle, transmitter in hand, while keeping an eye on the REMOTE KEYLESS ENTRY light. When the REMOTE KEYLESS ENTRY light begins to flash again, wait two minutes or longer before approaching the vehicle with the transmitter, or leave the transmitter out of range and remove the ignition key to complete the programming process.

    17

    Test the functionality of the RKE system while standing near the vehicle. If you continue to encounter issues with programming the RKE system, park the vehicle in a different area to avoid possible radio interference that may inhibit the programing process.

Subaru Forester Transmission Problems

Subaru Forester Transmission Problems

The Subaru Forester has recalls for transmission problems for the model years of 2001 and 2002 which concerned 172,564 Subaru Forester owners, according to Repair Pal. The newer models have not had recalls for this same transmission problem, but Subaru owners have complained about some other transmission problems with the Forester.

Transmission Recall

    2001 and 2002 Subaru Forester had a transmission recall from the manufacturer because the parking rod was installed incorrectly on over 170,000 vehicles. The Forester could not remain in park on the automatic transmissions of the Subaru because of this improper installation. The Forester owner could put the vehicle in park, but because of the parking rod being installed wrong it would roll or move as if the vehicle was in neutral. This transmission problem has a corrective action available from the dealership and does not cost the Subaru Forester owner anything for the repair.

Power-Train Problems

    The 2004 Subaru Forester was investigated by the National Highway Traffic Safety Association (NHTSA) for problems concerning the power-train of the transmission. No recall was instituted by the manufacturer because the concern from the NHTSA did not reveal a widespread problem, but some owners have experienced problems with the transmission power-train. The power-train of the Subaru runs the gears of the engine and transmission causing power to be supplied to the axles of the all-wheel drive or two-wheel drive Foresters. This transmission problem allowed the Forester to move and change gears, but caused the vehicle to jerk when changing from gear-to-gear. The Forester owner must take the Subaru back to the dealership to have this problem corrected.

Transmission Fluid

    The transmission fluid level must not get too low which causes the Subaru Forester to jerk during takeoff, slip when shifting gears, or not move at all. Another transmission problem attributed to low transmission fluid level has been in the 2006 Forester and causes the vehicle to slam into low gear when slowing down the Subaru or deceleration. Forester owners need to check the transmission fluid level periodically to ensure the fluid is not too low and add new fluid when the level shows a low fluid level on the dip-stick. The Subaru owner must not overfill the transmission fluid level which can create additional transmission problems.

How to Test the Camshaft Position Sensor With a Multimeter

How to Test the Camshaft Position Sensor With a Multimeter

The camshaft position sensor in your car or light truck operates on the principle of magnetic induction. When a magnetic field collapses around a conductor, it induces a voltage into the conductor. In the camshaft sensor, a magnetic field, supplied by a permanent magnet in the sensor, is allowed to surround a conductor in the sensor. As the camshaft turns, a toothed gear on the camshaft passes through the field and causes it to collapse. The result is an A/C sine wave voltage that the on-board computer uses to determine camshaft position.

Instructions

    1

    Unplug the electrical connector from the end of the sensor and remove the sensor. Consult your service manual for the exact procedures specific to your car as they vary from car to car. The typical camshaft position sensor is a cylindrical-shaped device, about 3 inches long and installed in the side of the engine block. The sensor must be removed for resistance testing with a multimeter.

    2

    Test for resistance by setting the multimeter to ohms and touching the two probes of the meter to the two pins in the electrical socket on the sensor. If resistance is infinite or 0 ohms, replace the sensor. Infinite resistance indicates an open circuit in the sensor, and 0 ohms indicates a shorted coil in the sensor.

    3

    Compare resistance measurements other than 0 ohms and infinite to the specifications for the sensor in the service manual. Replace the sensor if it does not fall within the specified range indicated in the service manual.

My Clutch Pedal Won't Come Back

My Clutch Pedal Won't Come Back

On a manual or stick shift car the clutch is what allows you to change gear. It is connected to a pedal on the floor by either a cable or a hydraulic link. The cable and the hydraulic link provide the auto-return so that after you press the pedal it comes back to its proper position and the clutch re-engages. Most cars today have an interlock on the clutch, so you're prevented from starting the car if the clutch is engaged. If the clutch won't come back, you may not be able to start the car, and you almost certainly won't be able to drive anywhere if you do. Fortunately, you may be able to temporarily fix the clutch so that you can get to a repair facility.

Instructions

    1

    Pump the clutch pedal to try and bring it back up. Sometimes this will create enough pressure to get it to function long enough for you to get home.

    2

    Open the hood and add clutch fluid to the reservoir. The location will vary depending on the make and model. Fill the reservoir to the recommended level and pump the clutch to work the air out of the system. Also look at the fluid to see if it looks dirty or cloudy. Dirty and cloudy fluid is a symptom of a leak somewhere in system.

    3

    Check the master cylinder and slave cylinder for leaks. Look around the seals for stains that may be evidence of fluid coming out. Also look for dents, cracks or other damage that could suggest a problem.

    4

    Check the clutch cable for stretches or breaks. Check the back of the pedal and make sure the cable is connected to the back. Also make sure the cable is still connected to the top of the clutch. Without tension on it, the cable can come loose from either place.

Sabtu, 16 April 2011

How to Troubleshoot a 1994 Mustang Front Wheel Shake

Diagnosing the cause of front wheel shake in your 1994 Mustang is done by testing and eliminating possible causes of the problem until the actual problem is pinpointed. The two areas of the Mustang that are most likely the causing wheel shake are the front brake rotors and the tires. A thorough inspection and testing of these two components will most likely reveal the cause of the wheel shake.

Instructions

    1

    Test-drive the Mustang. Pay attention to when the wheel shake occurs. If it occurs at all speeds and changes severity with increase in vehicle speed, it is most likely tire related. If it only occurs, or is worse when the brakes are applied, and can also be felt in the brake pedal, it is most likely brake-rotor related.

    2

    Park the Mustang on level ground and set the parking brake. Lift the front of the Mustang until the front wheels are off the ground using a floor jack positioned under the front crossmember. Slide jack stands under the front subframe and lower the car onto the stands.

    3

    Observe the front of the tire as you spin it by hand. A tread separation can be seen by looking at the horizon of the tire as it rotates for a hump in the tread. A visible separation cannot be repaired. The tire must be replaced.

    4

    Visually inspect the bead area of the wheel. Look for areas on the bead that a wheel weight seems to be missing from. Dirt and grime will gather under the weight. If the weight comes off, then a visible outline of the weight will be present on the wheel where it used to be. If a weight is missing, then have the wheels rebalanced.

    5

    Remove the front wheels using the lug wrench. Secure the rotor to the hub with two lug nuts installed on wheel studs. Attach the dial indicator to the magnetic base and position the base onto the flat portion of the strut that is attached to the steering knuckle behind the rotor.

    6

    Measure the run-out of the rotor. Loosen the thumbscrews on the dial indicator base and position the dial indicator so that the needle touches the rotor perpendicular to the rotor's friction surface. Spin the rotor slowly while observing the gauge on the dial indicator. Replace the rotor on the Mustang if there is more than .002-inch run-out.

Jumat, 15 April 2011

How to Check OBD2 Diagnostics on a Toyota Camry

How to Check OBD2 Diagnostics on a Toyota Camry

If a Toyota Camry was manufactured after 1996, then it will have the second generation of On-Board Diagnostic coding. If it was made before 1996, it will have a different coding system. This is important because an OBD2 scanner will not work on any vehicle predating 1996, and to access the OBD2 codes, you will need a scanner. You can buy a scanner at any major automotive retailer, and using it is fairly simple in terms of time and operation.

Instructions

    1

    Hook the OBD2 scanner up to the Toyota Camry's diagnostic outlet. You will find this below the steering wheel and dashboard.

    2

    Power up the diagnostic scanner.

    3

    Insert the Camry's key into the ignition and turn. This should activate the Toyota's electrical system. If the fault code does not appear on the scanner's screen, recheck the connection and start the Camry's engine.

    4

    Jot the alpha-numeric trouble code on a piece of paper. You will need to copy it verbatim, which means the letters as well as the numbers.

    5

    Turn the car and the scanner off. Unplug the scanner.

    6

    Go to a website with codes for a Toyota Camry (see Resources). You will have to do this because the Camry's owner manual will not have these code definitions.

    7

    Read the code definitions and make a decision on whether or not you need to take the car to a mechanic. Some repair issues are far more complex than others.

How to Diagnose a Car Steering Noise

How to Diagnose a Car Steering Noise

There are a lot of variables that affect noises that emanate, or seem to emanate, from your car's steering wheel. Most noises occur when turning the wheel. Car make and model is a factor, as is the type of steering system you have. Older cars may not have power steering, so you can eliminate possible power steering fluid issues. Newer cars and trucks almost always are equipped with power-assisted systems, whether it's rack-and-pinion or recirculating-ball steering. Your steering system interacts with many other parts, especially your suspension system, but most noises originating from steering maneuvers can be isolated and diagnosed.

Instructions

    1

    Turn on your engine and turn the steering wheel. Listen to the noise and note where in the wheel's turning ratio you hear the sound---when you start to turn, at either or both extremes of the turn, or always. Also note whether you need to be moving for the sound to occur (probably if you're hearing a "clunk").

    2

    Identify the type of sound you're hearing. This can be tricky, but anyone who's run low on power-steering fluid, had a loose or worn belt, or run into suspension problems can differentiate between noises. Mechanics might ask you if you're hearing a squealing sound, a groan, a whine, a screech, or a clunking sound (clunking is definitely the worst sound you want to hear when turning your wheel). Usually you can describe the noise sufficiently enough to make a preliminary diagnosis.

    3

    Check your power steering pump belt if you hear a whining sound. Tighten or replace it if that's the problem. If the noise is occurring only at the extreme ends of the wheel turns, and the belt seems fine, you may be okay. Screeching can simply indicate you're trying too forcefully to turn past the steering system's capability.

    4

    Inspect your power steering fluid level if you hear a squeal. The pump actually is pumping more air than oil. Most fluid reservoir dipsticks have two level markers---one indicates the cold engine level, the other is the running engine level. Older cars have one mark for hot engine level only. Fill your reservoir with manufacturer-specified fluid (or have your oil-change service station do it). With a very low fluid level, the whining sound will be accompanied by a difficulty in turning the wheel.

    5

    Look at the pump itself when a screech is heard. A worn pump can produce incredibly awful noises even with sufficient fluid levels. It may have to be replaced.

    6

    Check your suspension system if you're experiencing a clunking sound while turning the wheel, especially when the car is moving. You also may hear the sound when braking or traveling over bumps, and the wheel may vibrate. The possible problems are numerous, but none will be as simple to fix as pouring in a little fluid. Inspect your shocks, struts and other suspension-related parts. This can be a dangerous condition. Don't attempt to drive. Have your vehicle towed to a service station.

What Causes an Oil Press Gauge to Be on the High Side?

What Causes an Oil Press Gauge to Be on the High Side?

The oil in your engine is moved around via an oil pump, which is located in the oil pan. The pump picks up the oil and pushes it through the various oil galleries where it lubricates vital internal components, The oil then drains back to the oil pan, where it is again picked up by the pump. To monitor the amount of pressure the pump is working under, a pressure-sending unit is mounted in the system. This sending unit relays information to either a warning light,or a pressure gauge, depending upon how your particular vehicle is outfitted.

Cold Weather

    An oils' viscosity, or thickness, increases as the temperature decreases. An oil that is too thick will cause a higher than normal load upon the oil pump. During cold weather operations it is recommended a lighter viscosity oil be used. It is normal for the pressure gauge to read higher when the vehicle is cold, but if the reading does not return to normal when the engine is warm, a lighter viscosity oil should be considered.

Excessive Oil

    Never run the engine with an oil level higher than the full mark on the dipstick. Too much oil in the system puts undue strain upon the oil pump and can cause a high pressure reading. Always check the oil level when the engine is cold. It takes time for the oil to drain back into the oil pan after the engine has been operated.

Blocked Oil Filter

    The oil filter has many small openings through which the oil passes as it is being cleaned. These filters have an internal bypass system that allows oil to flow, even if they are blocked. If the filter is blocked and oil is being diverted through the filters' bypass system, it will increase the oil pressure.

Thickened Oil

    In some situations oil viscosity can actually increase over time. If the vehicle's fuel injectors are delivering too much fuel to the system, an increase of soot residue will result. This soot will find its way into the oil, where it will cause it to thicken, thereby raising pressure. Long periods of idling can also produce excessive amounts of soot.

Oil Gallery Blockage

    If the oil galleries are blocked or restricted, they force the oil pump to work harder. As the oil gallery holes become smaller, due to a buildup of deposits, the natural oil flow becomes severely restricted, raising internal oil pressure.

Kamis, 14 April 2011

1995 Ford Thunderbird Driver Side Door Won't Shut

The Ford Thunderbird was first introduced in 1955 and was manufactured until 2005. It became known as a personal luxury car because it was affordable yet fancier than the average automobile. The 1995 Thunderbird is part of the tenth generation of the car produced from 1989 through 1998. The rubber bushing that the door latch closes around can wear out, which results in the door being unable to close. You have three options to fix this: take it to a dealer, perform a temporary fix with tape or replace the bushing yourself.

Instructions

Temporary Fix

    1

    Open the latch on the door by lifting up on the external door handle, as if you were opening the car, then manually open the door latch.

    2

    Cut electrical or duct tape into two or three 2-inch strips. Make sure that the tape is thin enough to fit around the latch post, the horizontal metal bar on the door frame that the door latch closes around.

    3

    Wrap the tape around the post. Make sure that it is very smooth or else the latch will get hung up on the bubbles in the tape. This fix will work for about 50 to 100 closes of the door, depending on the quality of the tape that you used.

Permanent Fix

    4

    Obtain a used Thunderbird bushing from a scrapyard. It does not have to be the same model-year as your car; just measure the latch post on your car to make sure that the bushing will fit onto the post.

    5

    Cut the bushing along its length with the utility knife so that it opens up like a hot dog bun. Slip this onto the latch post of your vehicle. Make sure that the split is facing outwards so that you can access it.

    6

    Seal the cut that you made in the bushing with a strong adhesive, such as rubber cement or Gorilla Glue. Once the glue is dry, the bushing will be secured, and the door should close properly.

Signs of a Bad Speed Sensor

Signs of a Bad Speed Sensor

The speed sensor in a vehicle controls a number of different systems and can noticeably affect the way a car will run. The speed sensor can be on the transmission, differential, transaxle or speedometer head. A bad or malfunctioning speed sensor on a vehicle can cause a wide variety of problems ranging from an inconsistent speedometer to what appear to be transmission problems.

Service Engine Light

    If the speed sensor has gone out on your vehicle, the check engine light, or service engine light, will come on, indicating there is a problem. Depending on your vehicle, it may trigger other service lights.

Speedometer

    A primary function of the speed sensor is to tell how fast the vehicle is traveling. A vehicle with a broken or malfunctioning speed sensor will also probably be experiencing a malfunctioning speedometer. The speedometer may "jump," or jerk back and forth, even though the vehicle's speed does not change, and may stop working all together.

Cruise Control

    Speedometer problems also commonly lead to problems with the cruise control in a number of vehicles. If the vehicle's computer, or brain, cannot tell how fast it is traveling it will be unable to regulate the cruise control.

Transmission

    A malfunctioning speed sensor may cause problems with a vehicle's automatic transmission, depending on how it is malfunctioning.

    If the speed sensor is sending incorrect information to the vehicle's computer about how fast the vehicle is traveling, the vehicle may switch gears inappropriately, causing jerking and other assorted issues. The issues will depend on whether the vehicle is adapting for going faster or slower than it actually is. Either way, a bad speed sensor can wear out or damage a transmission if left unrepaired.

Stalling

    A vehicle with a completely dead speed sensor may stall because the vehicle is not sending the right signals to the computer and does not adjust properly to idle.

Rabu, 13 April 2011

How to Test Delco Remy Alternators

How to Test Delco Remy Alternators

Delco Remy is a company that manufactures alternators and starters. They've been in business for more than 100 years and are now making engine parts that have high amperage output and can withstand intense operating temperatures. Use a voltmeter to test your Delco Remy alternator for soundness and check the battery's output at the same time. The battery supplies the power to crank the engine, and the alternator supplies the battery with recharging power while the engine is running. Both need to be healthy for your car to run properly.

Instructions

    1

    Lift the hood of your car and find the battery while the engine isn't cranked. The battery is a solid, rectangular component usually near a fender. The battery may have a plastic cover. Remove the cover if it does.

    2

    Identify the positive and negative battery posts. The battery posts are the raised terminals that the battery cables are connected to. The positive battery post has a red cable connector and a plus sign beside it. The negative post has a black cable connector and a minus sign beside it.

    3

    Attach the positive, or red, voltmeter test lead to the positive battery post, and the negative, or black, voltmeter test lead to the negative battery post. Check the reading on the voltmeter before cranking the engine. The meter will be testing the voltage in the battery. A reading between 12.5 and 12.8 volts is normal for a strong battery.

    4

    Crank the engine and check the voltmeter readout again. While the engine is running, the voltmeter measures the volts in the alternator. A reading between 13.6 and 14.3 volts is considered optimal for a healthy alternator. A lesser reading is an indication the Delco Remy alternator may need replacing.

How to Check the DTC Code on a Subaru Impreza

How to Check the DTC Code on a Subaru Impreza

The diagnostic trouble codes on a Subaru Impreza are relatively easy to check. These codes and the on-board diagnostic system as a whole are interconnected with your Subaru's service warning light on the dashboard, behind the steering wheel. If the light is not lit, then you likely do not have a pressing need to access the diagnostic system. However, dash bulbs can and do burn out, and if you think you have a problem, it's best to check. All you need is a diagnostic scanner fluent in OBD-II codes. Buying a scanner will pay for itself over the years.

Instructions

    1

    Ensure that the engine is turned all the way off, including the electrical components.

    2

    Locate the Subaru's OBD-II diagnostic jack. It should be in the front of the car and in plain view. Law requires that this jack require no tools for access. In most models of most cars sold in the United States, the jack is located beneath the dashboard and steering wheel on the driver side of the car.

    3

    Connect the scanner to the jack. The scanner features an electrical cable with a wide, multiple-pin plug that should easily slide into place with a firm push.

    4

    Boot up the scanner and wait a few seconds for it to become fully operational.

    5

    Turn on the Sabaru and wait for the car to establish a working connection with the OBD-II scanner. This should take only a few seconds.

    6

    Look at the scanner's read-out screen. If there is a diagnostic trouble code in the Subaru's computer, it should display at this time. If the Subaru's diagnostic system has not found a problem, then no trouble code should appear.

How to Troubleshoot a 2002 Lesabre

How to Troubleshoot a 2002 Lesabre

The Buick LeSabre is a full-size sedan manufactured by General Motors. The LeSabre enjoyed a lengthy production, beginning in the 1959 model year and ending in 2005. Common problems with the 2002 LeSabre revolve around the intake manifold gasket, air flow and crankshaft position sensors and the water pump. These are the main issues of concern for the LeSabre.

Instructions

    1

    Inspect common trouble areas such as the fan, serpentine and timing belts, battery, spark plugs and tire pressure. Check the oil, fuel and fluid levels as well.

    2

    Examine the intake manifold. If leaking oil is present, the gaskets need replacing.

    3

    A stalling engine may be due to faulty crankshaft position or mass air flow sensors that will need to be replaced.

    4

    If the engine is prone to overheating, check the area of the vehicle beneath the water pump for leaking coolant. If the water pump is leaking coolant, it will need to be replaced.

Selasa, 12 April 2011

Transmission Problems With the Pontiac Grand Am

The Pontiac Grand Am, a compact car available with a manual or automatic transmission, was introduced in 1973. Edmunds.com contends the Grand Am, although affordable, is "unrefined" and "uncomfortable." Additionally, multiple fifth generation Grand Am models completed from 1999 through 2005, suffer from automatic transmission problems.

Problem

    Pontiac technical service bulletins (TSBs) report that difficulty shifting is a common problem amongst 1999 to 2005 Grand Am models. Shifting difficulties include harsh shifts, slippage between gears and not being able to shift into drive or reverse. TSBs also report user difficulty in shifting from first to second and third to fourth gears.

Cause

    The primary culprit for the Grand Am's shifting inadequacies is its transaxle connected to the shifter. A leaking transaxle may result in harsh shifts and slipping, because it can no longer provide the necessary lubrication.

Solution

    If you regularly drive under harsh conditions, the owner's manual suggests checking and changing the transaxle fluid and filtering every 50,000 miles. Transaxle leakage requires axle seal replacement, which costs approximately $108 per seal to replace as of February 2011, according to MSN Auto.

Problems With Getting No Spark From the Ignition Coil & Ignition Issues

Problems With Getting No Spark From the Ignition Coil & Ignition Issues

Certain requirements must be met for an ignition coil to produce the high-voltage spark that fires an engine. Problems associated with meeting these requirements can be as simple as a corroded wire or weak battery. More complicated issues may also contribute to spark loss, but basic conditions are still the general means for good function of any ignition system. Knowing what to look for when troubleshooting ignition systems can allow proper decisions to be made when selecting repair procedures or replacement parts.

Power

    Two positions of the ignition switch provide power to the positive primary post of the ignition coil. In the "start" position, the switch energizes the starter motor, and full battery voltage is directed to the coil while the engine cranks. Once the engine starts, the switch is released to the "run" position. The coil still receives voltage, but the amount may be reduced by a resistor in the "run" circuit. In either instance the supplied voltage must be continuous. Examine the battery, ignition switch and circuitry if the coil primary voltage is errant or not present at all.

Signal

    With no external signal to the coil negative primary post, voltage would travel through the ignition coil windings without inducing any secondary spark. A switch, or signaling device, triggers an interruption in the circuit. High voltage is then generated in the coil windings. Voltage transformation produced by the interruption coincides to each spark generated. Older ignition systems used breaker points to interrupt the circuit, while more modern systems "sense" the need for spark by means of a hall-effect switch or crankshaft position sensor. The ignition module uses the information to time spark generation. Test these components if the energized coil fails to function.

Flow

    Normally, the high secondary voltage produced by an ignition coil is quite powerful. You can replace the secondary coil wire on an engine that uses one with an equal length of vacuum hose and the engine will start and run. The powerful spark will travel down the hollow hose to the distributor cap, but the engine will stall under any load because of the weakened spark. However, the coil will not fire across a wide gap or through thick corrosion. Ensure secondary spark conductors are complete circuits with good connections and insulation to gain successful voltage delivery.

Open Circuits

    Any break in a conductive material, like a wire, creates an open circuit. An open circuit behaves as though it were switched off. The windings in an ignition coil are no more than thin wires, and open circuits can occur inside the coil. You can test the continuity of coil windings by measuring the resistance with an ohmmeter. Corroded connections can have enough resistance to essentially create an open circuit. Bad ground connections have the same effect as any open circuit, and battery and engine grounds should not be overlooked when diagnosing a "no spark" condition.