GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Astro - 4WD 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Service All-Wheel Drive Indicator Always On

Circuit Description

The SERVICE AWD indicator is located in the instrument panel cluster (IPC). It receives ignition voltage through the IPC 10 amp gage fuse through the ignition 1 voltage circuit. The ignition 1 voltage circuit also supplies all of the gages with ignition voltage. The transfer case shift control module controls the SERVICE AWD indicator by sending the IPC a Class 2 message. This indicator may be controlled with the scan tool using the IPC output controls.

Test Description

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

  1. This step determines whether the failure is the result of a faulty transfer case shift control module or the IPC.

Step

Action

Yes

No

Schematic Reference: Transfer Case Control Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn the ignition ON, with the engine OFF.
  2. Install a scan tool.
  3. Using the scan tool go to instrument panel cluster output controls.
  4. Use the scan tool in order to command the SERVICE 4WD Message OFF.

Does the SERVICE 4WD Message turn OFF?

Go to Step 3

Go to Instrument Panel Assembly Replacement in Instrument Panel, Gages, and Console

3

Replace the transfer case shift control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the repair?

Go to Step 4

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4
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle in order to determine if the symptom has been corrected.

Is the symptom still present?

Go to Step 2

System OK