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 lamp by sending the IPC a Class 2 message. This lamp 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 if there is a class 2 communication error or if the IPC is faulty.

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 | Does any module set a DTC beginning with a 'U'? | Go to Scan Tool Does Not Communicate with Class 2 Device | Go to Step 3
3 | Replace the instrument panel cluster. Refer to Instrument Cluster Replacement. Did you complete the repair? | Go to Step 4 | --
4 |

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