GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The all-wheel drive (AWD) disable indicator lamp is located in the instrument panel cluster (IPC). Ignition 1 voltage is supplied to the IPC when the ignition switch is in the START or RUN position. When the powertrain control module (PCM) receives a signal from the differential clutch pump actuator check valve, indicating an overtemperature condition, or a signal from the antilock brake system (ABS) controller indicating a speed differential between wheels, the AWD system is disabled. The PCM then sends a class 2 signal to the IPC, illuminating the AWD disable indicator.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests for an intermittent condition.

  2. This step determines if the failure is the result of a faulty instrument cluster.

Step

Action

Yes

No

Schematic Reference: Differential Lock Schematics

1

Did you perform the Diagnostic System Check - Rear Axle Controls?

Go to Step 2

Go to Diagnostic System Check - Locking/Limited Slip Rear Axle

2

Verify the fault is present.

Does the system operate normally?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn ON the ignition, with the engine OFF.
  2. Install a scan tool.
  3. Use the scan tool to command the AWD system disabled.

Does the AWD Disable indicator turn ON?

Go to Step 4

Go to Step 5

4

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 3.4L.

Did you complete the replacement?

Go to Step 6

--

5

Replace the instrument panel cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.

Did you complete the replacement?

Go to Step 6

--

6

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3