Test E

Pinpoint Test E: The Vehicle Does Not Shift Between 4-Wheel Drive Auto and 4L Correctly

Normal Operation

With the key in the ON position, the 4x4 module (PCM) receives the operator's choice of four-wheel drive selection from the mode select switch (MSS). The 4x4 module (PCM) then controls the electric clutch and shift motor. If the transfer case is not responding to the operator's intentions, systematically check all inputs and outputs to the 4x4 module (PCM).

Possible Causes

- Battery junction box (BJB) fuses:
- 8 (30A) - 4x4 motor
- BJB fuse 15 (15A) - PCM
- BJB fuse 18 (20A) - 4x4 module (PCM)
- BJB fuse 17 (5A) - transfer case clockwise (CW) and counterclockwise (CCW) relay coils
- Central junction box (CJB) fuse 12 (5A) switch.
- Transfer case CW relay.
- Transfer case CCW relay.
- 4L indicator
- 4L LED
- mode select switch (MSS)
- transfer case
- shift motor
- 4x4 module (PCM)
- ABS module
- circuit 779 (BN)
- TR (Trans.)
- CAN