Initial Inspection and Diagnostic Overview

1. The interior lighting system is a Generic Electronic Module (GEM)/Central Timer Module (CTM) controlled system.

NOTE: The GEM/CTM must be reconfigured upon replacement. Refer to the scan 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 for obvious signs of mechanical and electrical damage.







VISUAL INSPECTION CHART

4. If the concern remains after the inspection, connect the scan tool to the Data Link Connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the scan tool menu. If the scan tool does not communicate with the vehicle:
^ check that the program card is properly installed.
^ check the connections to the vehicle.
^ check the ignition switch position.

5. If the scan tool still does not communicate with the vehicle, refer to the scan tool manual.
6. Perform the DATA LINK DIAGNOSTICS test. If the scan tool responds with:
^ CKT914, CKT915 or CKT7O = ALL ECUS NO RESP/NOT EQUIP, refer to Module Communications Network(Information Bus).
^ NO RESP/NOT EQUIP for GEM/CTM, go to Pinpoint Test A. Test A: No Communication With The GEM/CTM
^ SYSTEM PASSED, retrieve and record the continuous Diagnostic Trouble Codes (DTCs), erase the continuous DTCs and perform self test diagnostics for the GEM/CTM.

7. If the DTCs retrieved are related to the concern, go to GEM/CTM Diagnostic Trouble Code (DTC) Index to continue diagnostics. GEM/CTM Diagnostic Trouble Code (DTC) Index
8. If no DTCs related to the concern are retrieved, proceed to Symptom Chart to continue diagnostics. Symptom Related Diagnostic Procedures