Flow of Diagnosis

NOTE: The GEM/CTM must be reconfigured upon replacement. Refer to the New Generation STAR (NGS) Tester help screen on the configuration card to program the tire size and axle ratio.

1. Verify the customer concern by operating the 2WD/4WD engagement.





2. Visually inspect for obvious signs of mechanical and electrical damage; refer to the chart:
3. If the concern remains after the inspection, connect the New Generation STAR (NGS) Tester to the Data Link Connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the NGS menu. If the NGS 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.
4. If the NGS still does not communicate with the vehicle, refer to the Tester manual.
5. Perform the DATA LINK DIAGNOSTIC TEST. If the NGS responds with:
- CKT914, CKT915 or CKT70 = ALL ECUS NO RESP/NOT EQUIP, diagnose Multiplex Communication Network concerns.
- NO RESP/NOT EQUIP for Generic Electronic Module (GEM)/Central Timer Module (CTM), go to Pinpoint Test D. D: No Communication With Module - GEM
- SYSTEM PASSED, retrieve and record the continuous Diagnostic Trouble Codes (DTCs), erase the continuous DTCs and perform self-test diagnostics for the GEM.
6. If the DTCs retrieved are related to the concern, go to the GEM/CTM Diagnostic Trouble Code (DTC) Index to continue diagnostics.
7. If no DTCs related to the concern are retrieved, proceed to Symptom Chart. Symptom Related Diagnostic Procedures