GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 HUMMER 🢒 2008 🢒 H3 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Service Indicator Always On

Circuit Description

The Service 4WD indicator is located in the instrument panel cluster (IPC), and shares the common power and ground of the IPC. The transfer case shift control module controls the Service indicator by sending the IPC a Class 2 message. This indicator may be controlled with the scan tool using the IPC device 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 malfunctioning transfer case shift control module or the IPC.

Step

Action

Yes

No

Schematic Reference: Transfer Case Control Schematics

Connector End View Reference: Component Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Observe the Service 4WD parameter input/output in the instrument panel cluster (IPC) Scan Tool Data List.

Is the Service 4WD indicator commanded ON?

Go to Step 3

Go to Step 4

3

Replace the transfer case shift control module. Refer to Control Module References for replacement, setup and programming.

Did you complete the repair?

Go to Step 5

--

4

Replace the IPC. Refer to Instrument Cluster Replacement .

Did you complete the repair?

Go to Step 5

--

5
  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 1

System OK