Test C: The Vehicle Does Not Shift Between 4X4 High and 4X4 Low Modes Correctly

Pinpoint Test C: The Vehicle Does Not Shift Between 4x4 High And 4x4 Low Modes Correctly

Normal Operation
The 4x4 HIGH to 4x4 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, transmission range selection and brake applied must be met before this shift can occur. Systematically check the necessary inputs and outputs of the 4WD control module components and the transfer case.

Possible Causes
^ 4WD control module
^ Transmission range (TR) sensor
^ Brake ON/OFF (BOO)
^ Vehicle speed signal (VSS)
^ Mode select switch (MSS)
^ Transfer case shift motor
^ Encoder (integral to transfer case shift motor)
^ Transfer case

C1-C4:

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