Test Description

WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

2: This step determines if the condition is with the MIL control circuit or the PCM.

Malfunction Indicator Lamp (MIL) Always On

Step	Action	Yes	No
Schematic Reference: Instrument Cluster Schematics or Engine Controls Schematics Connector End View Reference: Displays and Gages Connector End Views or Powertrain Control Module Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Turn OFF the ignition. Disconnect the powertrain control module (PCM). Turn ON the ignition, with the engine OFF. Observe the malfunction indicator lamp (MIL). Is the MIL illuminated?	Go to Step 3	Go to Step 5
3	Remove the instrument panel cluster (IPC). Refer to Instrument Cluster Replacement . Test the MIL control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 6	Go to Step 4
4	Replace the IPC. Refer to Instrument Cluster Replacement . Did you complete the replacement?	Go to Step 6	-
5	Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?	Go to Step 6	-
6	Turn the ignition OFF for 30 seconds. Start the engine. Observe the MIL. Does the MIL operate correctly?	Go to Step 7	Go to Step 2
7	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	Go to Diagnostic Trouble Code (DTC) List - Vehicle	System OK