Test Description

WARNING: This page is about a different car, the 2002 Pontiac Grand Am and 2002 Oldsmobile Alero. However, it is still accessible from the selected car via links, so may be relevant.

Powertrain Control Module (PCM) diagnostic system check is an organized approach to identifying a condition that is created by a malfunction in powertrain control system. Diagnostic system check must be starting point for any driveability concern. Diagnostic system check directs service technician to next logical step to diagnose concern. Understanding and correctly using procedure reduces diagnostic time, and prevents replacement of good parts.

If PCM stores multiple powertrain DTCs, diagnose DTCs in following order:

Component level DTCs, such as sensor DTCs, solenoid DTCs, and relay DTCs. Diagnose multiple DTCs within this category in numerical order. Begin with lowest numbered DTC, unless diagnostic table directs otherwise.
System level DTCs, for example, misfire DTCs, fuel trim DTCs, and catalyst DTCs.