Pinpoint Test J: the Transfer Case Does Not Shift Between 2H and 4H Modes Correctly

Pinpoint Test J: The Transfer Case Does Not Shift Between 2H And 4H Modes Correctly

Normal Operation

The mode select switch communicates the operator's choice to the 4x4 module. The 4x4 module then controls the transfer case motor and pulse vacuum hublocks (PVHs) as necessary. If the vehicle is not responding to the operator's intentions, systematically check the necessary inputs and outputs of the 4x4 module, components of the transfer case, PVH components and axle shafts. Check all circuits for opens and shorts to power or ground.

Possible Causes
- Transfer case
- PVH solenoid
- Vacuum leaks
- 4x4 module
- Front axle assembly
- Mode select switch (MSS)
- Relays