Test C: The Vehicle Does Not Shift Between 4WD High and 4WD Low Correctly

Pinpoint Test C: The Vehicle Does Not Shift Between 4WD High and 4WD Low Correctly
Refer to Vehicle/Diagrams, Four-Wheel Drive System for schematic and connector information.

Normal Operation
The high-low shift occurs when the reduction shift fork moves the high-low collar to lock the planetary gear set to the output shaft. The torque transmitted through the sun gear from the input shaft turns the front planetary gear set assembly. The front planetary gear set assembly, now engaged, provides transfer case speed reduction. Certain criteria, such as vehicle speed and transmission range selection must be met before this shift can occur. Systematically check the necessary inputs and outputs of the 4X4 control module, components of the transfer case and halfshafts.

This pinpoint test is intended to diagnose the following:
^ Transmission neutral switch
^ ABS wheel speed inputs
^ Controller area network (CAN) communication network

C1-C3: