Diagnostic codes are created when a malfunction occurs in the engine of your 1988 Chevy Cheyenne truck. The engine interprets the malfunction, creates a code and stores it within the computer for your retrieval. Accessing the code and finding out what it means helps you track down the source of the trouble and repair it. Use a scanner to pull the code or go to a car parts store like Auto Zone or Napa Auto Parts for a diagnostic check free of charge.
Retrieve the engine codes from your 1988 Chevy Cheyenne. Using a diagnostic scanner is the easiest way to pull trouble codes. Plug the scanner into the test port under the driver's side dash, turn the key "On" and follow the prompts on the scanner to read the codes. The codes display on the screen of the scanner.2
Consult a repair or owner's manual for the meanings to the codes. Each code indicates a different system malfunction, pointing to the source of the problem. Codes are also available online. Click the link in "Resources" for a list of GM codes and their meanings.3
Address the indicated problem. For instance, a code indicating a rich fuel-to-air ratio usually indicates a bad oxygen sensor. Replace the suspected defective part.4
Clear the original trouble code. Use the scanner as in step 1, first plugging it in and turning the key "On." Pull the codes and select the option to clear them.5
Test the Chevy for trouble codes again after driving several times. If the repairs addressed the problem, the codes won't reappear.