Test Description

WARNING: This page is about a different car, the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers in the diagnostic test procedures.

1

The System Check MUST be performed before proceeding with this diagnostic test. Failure to perform the System Check will result in misdiagnosis.

2

With ignition on, with engine off, the PCM should continuously illuminate the MIL.

3

The scan tool will command BOTH the PCM and AF ECM to turn the MIL OFF.

5

This step checks if a PCM system failure is the cause of the inoperative MIL. The most likely cause of no MIL and a no-start is a loss of voltage to the PCM.

7

This step tests for an open MIL Input circuit. The PCM should always command the MIL ON when the ignition is ON and engine is OFF.

8

This step tests for an open MIL control circuit or IPC.