Transfer Case: Testing and Inspection

GENERAL NOTES:
A problem with the transfer case may be caused by the engine, the driving conditions, the transfer case itself, or the electrical control system. When troubleshooting, therefore, begin with the points that can be inspected quickly and easily. The recommended troubleshooting sequence is described below.





On-board Diagnosis System Inspection

Check the warning alarm for operation. When the ignition switch is turned to OFF, the warning alarm is cancelled because there is no memory in the 4WD control module. When the ignition switch is tuned to ON, the warning alarm will reappear only if the problem still exists.





Electrical Signal Inspection
Check the signals to/from the 4WD control module.




System Operation Inspection
Check operation of the Multi-Mode 4WD system.




Symptom Troubleshooting
Check the Multi-Mode 4WD system for malfunctions.





Quick Diagnosis Chart
1. Problems indicated by "X" in the Exclusion column may be normal operation
2. The numbers in the chart indicate the order of inspection for easy detection of malfunction.

ON-BOARD DIAGNOSIS SYSTEM/INSPECTION










Fail Mode Function
The warning alarm will sound if a malfunction is found in the change motor or electrical circuit. While in fail mode, the warning alarm will sound whenever the 4WD/2WD shift switch or differential lock switch is activated. The fail mode function is cancelled when the ignition switch is turned to OFF. If a malfunction occurs in either of the position switches while the change motor is running, the 4WD control module sets the mode to 2WD. If a malfunction occurs in either of the limit switches while shifting, the 4WD control module sets the motor step position.






CAUTION MODE FUNCTION

The caution alarm will sound as shown if the 4WD/2WD switch is activated while driving in 4WD (Locked) mode. The proper sequence is to first turn off the center differential lock switch to set 4WD (Free) mode; then activate the 4WD/2WD shift switch to set 2WD mode.






ELECTRICAL SIGNAL INSPECTION
Check the electrical signals to/from the 4WD control module.

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