Pinpoint Test U: The Vehicle Does Not Shift Between 4H and 4L Modes Correctly
Four Wheel Drive (4WD) Systems - Electronic Shift
Pinpoint Test U: The Vehicle Does Not Shift Between 4H and 4L Modes Correctly
Refer to Wiring Diagram Set 34, Four-Wheel Drive Systems for schematic and connector information. Diagrams By Number
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 (TR) selection must be met before this shift can occur. Systematically check the necessary inputs and outputs of the Transfer Case Control Module (TCCM), components of the transfer case, Integrated Wheel End (IWE) components and halfshafts.
- DTC C1729:00 Transfer Case Unable to Transition Between 4H and 4L - Fault sets when target shift motor position is not reached after the maximum number of allowed blocked shift retries for 4H to 4L or 4L to 4H. Requested shift motor position is not reached.
This pinpoint test is intended to diagnose the following:
- Transmission neutral switch
- ABS wheel speed inputs
- High Speed Controller Area Network (HS-CAN)
PINPOINT TEST U: THE VEHICLE DOES NOT SHIFT BETWEEN 4H AND 4L MODES CORRECTLY
WARNING: When directed to drive the vehicle as part of this test, drive the vehicle on a hard surface in an area without traffic to prevent a crash. Failure to follow these instructions may result in personal injury.
