4x4 not working (91-94)
The 4x4 system can be shifted on the fly into 4x4 high at anytime. If pressing 4x4 fails to activate 4x4 (The dash and button 4x4 lights are off) then you have a failure in the system (Dash button, 4x4 module,
Shift motor). If you listen carefully you should be able to hear the relays in the
4x4 module when you press the 4x4 button. If you cannot hear the relays recruit a friend to sit near the module and listen. If the relays make noise it indicates the 4x4 module has received input from the dash button and the problem lies in either the 4x4 computer or the shift motor. The most common problem is a
broken stop bumper within the shift motor that allows the
geared position sensor to travel outside of its operational range. When this occurs the 4x4 module becomes lost, and will no longer shift the T-Case as it cannot determine the current position of the T-case selector shaft.
See the
Shift motor rebuild thread on how to fix this.
If you cannot hear the 4x4 relays then you will need to verify the 4x4 module is working.
Checking the 4x4 module (rear trunk).
Unplug the two connectors that plug directly into the module (left side), turn the key on and push the reset/test button on the module. The LED should flash four or five times and stop. If the LED flashed the four or five times, the module believes it is ok internally, and you'll need to check the external parts like the 4X4 switch, shift motor, magnetic clutch and wiring harness. If the LED did not flash at all or kept flashing continually, the module is telling you that it is damaged internally. (check for power & ground).
Click a thumbnail for full size image
To engage 4x4 Low you must:
- 1st be in 4x4 high
- Transmission in Neutral
- Clutch depressed (manual transmission)
- Foot on Brake (mph<3)
- Now Press 4x4 Low
