For 1990-2009 cars

### 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 condition 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: Transfer Case Control Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Disconnect the transfer case shift control module connectors C1 and C2. Is the Service 4WD indicator still ON? | Go to Step 4 | Go to Step 3
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 instrument panel cluster. 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 to determine if the symptom has been corrected.

Is the symptom still present?

Go to Step 1

System OK