Test C

Pinpoint Test C: The Vehicle Does Not Shift Between 4WD HIGH And 4WD LOW Modes Correctly

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 all inputs and related circuits. If the inputs prove out, check the transfer case shift motor and clutch along with the associated circuitry.


Possible Causes

- digital transmission range (TR) sensor

- circuit 463 (RD/WH)

- circuit 976 (OG)

- brake pedal position (BPP) switch

- circuit 511 (LG)

- mode select switch (MSS)

- circuit 784 (LB/BK)

- circuit 464 (BK/PK)

- 4WD control module

- circuit 762 (YE/WH)

- circuit 763 (OGIWH)

- circuit 764 (BNIWH)

- circuit 770 (WH)

- circuit 771 (VT/YE)

- transfer case shift motor

- transfer case clutch

- circuit 777 (YE)

- circuit 778 (OG)

- transfer case shift shaft transfer case gearmotor encoder assembly

PINPOINT TEST C: THE VEHICLE DOES NOT SHIFT BETWEEN AUTOI4WD HIGH AND 4WD LOW MODES CORRECTLY