76-1

VTM-4 DTC Troubleshooting: 76-1

DTC 76-1: Rear Differential Clutch Warning System

NOTE: Before you troubleshoot, review the general troubleshooting information. Initial Inspection and Diagnostic Overview

1. Turn the ignition switch to ON (II).

2. Make sure the HDS communicates with the vehicle and the VTM-4 control unit. If it doesn't, troubleshoot the DLC circuit. Testing and Inspection

3. Clear the DTC with the HDS.

4. Test-drive the vehicle at speeds over 25 mph (40 km/h), while keeping the engine speed below 2,500 rpm for at least 30 seconds.

NOTE: Be careful not to overheat the rear differential clutch system.

5. Check for DTCs with the HDS.

Is DTC 76-1 indicated?
YES - Go to step 6.

NO - Intermittent failure, the system is OK at this time.


6. Check for DTCs in the VSA system with the HDS.

Are there any VSA DTCs indicated?
YES - Go to the indicated DTC's troubleshooting.

NO - Go to step 7.


7. Turn the ignition switch to LOCK (0).

8. Raise the vehicle on a lift, and make sure it is securely supported.

9. Spin the rear wheels by hand, and check for rear brake drag.

Are the rear brakes dragging?
YES - Repair cause of rear brake drag, and retest.

NO - Go to step 10.


10. Turn the ignition switch to ON (II).

11. Measure the voltage between VTM-4 control unit connector terminals A3 and A5 to body ground while rotating the appropriate wheel (1 rotation/second).





Is there about 2.0 to 3.0 V?
YES - Go to step 19.

NO - Go to step 12.






12. Turn the ignition switch to LOCK (0).

13. Disconnect the VTM-4 control unit and the VSA modulator-control unit connectors.

14. Check for continuity between VTM-4 control unit connector terminals A3 and A5 to body ground.

Is there continuity?
YES - Repair short to ground in the wire between VTM-4 control unit (A3 and/or A5) and the VSA modulator-control unit.

NO - Go to step 15.






15. Connect VTM-4 control unit connector terminals A3 and A5 to body ground with the jumper wires.






16. Check for continuity between the VSA modulator-control unit 46P connector terminals and body ground.





Is there continuity?
YES - Go to step 17.

NO - Repair open in the wire between VTM-4 control unit (A3 and/or A5) and the VSA modulator-control unit.






17. Check for poor connections or loose terminals at the VTM-4 control unit and the VSA modulator-control unit connectors. If the connections are OK, substitute a known-good VTM-4 control unit Service and Repair and recheck. If the symptom/indication goes away with the known-good VTM-4 control unit, replace the original VTM-4 control unit. Service and Repair

18. Test-drive the vehicle at speeds over 25 mph (40 km/h), while keeping the engine speed below 2,500 rpm for at least 30 seconds.

NOTE: Be careful not to overheat the rear differential clutch system.

19. Check for DTCs with the HDS.

Is DTC 76-1 indicated?
YES - Replace the VSA modulator-control unit. Service and Repair

NO - The system is OK at this time.