Initial Inspection and Diagnostic Overview

1. The interior lighting system is a Generic Electronic Module (GEM) controlled system.

NOTE: The Generic Electronic Module (GEM) must be reconfigured upon installation. Refer to the diagnostic tool help screen on the configuration card to program axle ratio and tire size.

2. Verify the customer concern by operating the interior lighting system.
3. Visually inspect the following for obvious signs of mechanical and electrical damage.

Visual Inspection Chart:

4. If the concern remains after the inspection, connect the diagnostic tool to the Data Link Connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the diagnostic tool menu. If the diagnostic tool does not communicate with the vehicle:
^ check that the program card is correctly installed.
^ check the connections to the vehicle.
^ check the ignition switch position.
5. If the diagnostic tool still does not communicate with the vehicle, refer to the diagnostic tool manual.
6. Carry out the DATA LINK DIAGNOSTICS test. Pinpoint Test PC (Precheck)
If the diagnostic tool responds with:
^ CKT914, CKT915 or CKT70 = ALL ECUS NO RESP/NOT EQUIP, refer to Module Communications Network (Information Bus).
^ NO RESP/NOT EQUIP for GEM, Multifunction Electronic Control Module (General Module).
^ SYSTEM PASSED, retrieve and record the continuous Diagnostic Trouble Codes (DTCs), erase the continuous DTCs and carry out self-test diagnostics for the GEM.
7. If the DTCs retrieved are related to the concern, go to the GEM Diagnostic Trouble Code (DTC) Index to continue diagnostics. Diagnostic Trouble Code Tests and Associated Procedures
8. If no DTCs related to the concern are retrieved, proceed to the Symptom Chart to continue diagnostics. Symptom Related Diagnostic Procedures