Diagnostic Notes

The symptoms and actions in this section are used when trouble codes are not available for direction to a component failure.

In order to save valuable time and possibly correct a simple problem, always start with the FLOW OF DIAGNOSIS. Performing a thorough visual and physical check, verifying that the MPI System is operating normally, and to check for any stored trouble codes.

NOTE: Except when attempting to diagnose a cold driveability complaint, it is essential that the vehicle be properly warmed up to operating temperature. The vehicle should be driven for 10 to 20 minutes, to ensure that the catalytic converter and feedback systems are functioning as designed during diagnosis. If this is not achieved, tests results may be grossly inaccurate.

The following symptom charts contain possible causes for each symptom and cover several engines. These procedures should be done in a logical order, easiest to check or most likely cause first. They are not meant to be done in consecutive order.

Refer to Powertrain Management/Computers and Control Systems/Diagrams/Electrical in order to determine if the vehicle uses a particular system or component.