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Pinpoint Test D: The Vehicle Does Not Shift Between Four-Wheel Drive (4WD) High and Four-Wheel Drive (4WD) Low Correctly




Four Wheel Drive (4WD) Systems - Electronic Shift

Pinpoint Tests

Pinpoint Test D: The Vehicle Does Not Shift Between Four-Wheel Drive (4WD) High and Four-Wheel Drive (4WD) Low Correctly

Refer to Wiring Diagram Set 34, Four-Wheel Drive System 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 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

PINPOINT TEST D: THE VEHICLE DOES NOT SHIFT BETWEEN FOUR-WHEEL DRIVE (4WD) HIGH AND FOUR-WHEEL DRIVE (4WD) LOW CORRECTLY

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D1 CHECK THE 2WD TO 4WD SHIFT

- Drive the vehicle and shift the Mode Select Switch (MSS) from 2H to 4H.
- Does the vehicle shift between 2-Wheel Drive (2WD) and Four-Wheel Drive (4WD) correctly?

Yes
GO to D2.

No
GO to Pinpoint Test C. Pinpoint Test C: The Vehicle Does Not Shift Between 2-Wheel Drive (2WD) and Four-Wheel Drive (4WD) Modes Correctly

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D2 CHECK THE 4X4 HIGH TO 4X4 LOW SHIFT

- Drive the vehicle and shift the MSS from 4H to 4L with:
- vehicle speed less than 5 km/h (3 mph).
- transmission in NEUTRAL (or clutch pedal applied).

- Does the transfer case shift from 4X4 HIGH to 4X4 LOW correctly and is the concern related to a clunk noise during the shift?

Yes
Transmission neutral drag is excessive. REFER to Automatic Transmission - 5R44E and 5R55E Testing and Inspection for transmission diagnosis.

No
GO to D3.

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D3 CHECK THE NEUTRAL SAFETY SWITCH (NTRL_SW) AND ABS MODULE WHEEL SPEED PIDs

- Enter the following diagnostic mode on the scan tool: DataLogger - 4X4 Control Module.
- A. Vehicles equipped with automatic transmissions: Monitor the NTRL_SW PID while shifting the transmission through gear ranges.
- B. Vehicles equipped with manual transmissions: Monitor the NTRL_SW PID while applying the clutch pedal.
- Enter the following diagnostic mode on the scan tool: DataLogger - ABS Module.
- C. Monitor the ABS module wheel speed PIDs.
- Left Front Wheel Speed Sensor (LF_WSPD)
- Left Rear Wheel Speed Sensor (LR_WSPD)
- Rear Differential Wheel Speed (R_DIF_SPD)

- A. Vehicles equipped with automatic transmissions: Does the 4 NTRL_SW indicate NEUTRAL when the transmission is shifted to NEUTRAL?

B. Vehicles equipped with manual transmissions: Does the NTRL_SW PID indicate on when the clutch pedal is applied?

C. Do the wheel speed PIDs indicate 0 km/h (0 mph)?


Yes
If all 4 PIDs are accurate, GO to Pinpoint Test C. Pinpoint Test C: The Vehicle Does Not Shift Between 2-Wheel Drive (2WD) and Four-Wheel Drive (4WD) Modes Correctly

No
A. REFER to Automatic Transmission - 5R44E and 5R55E Testing and Inspection for further diagnosis of the Transmission Range (TR) sensor and the CAN communication network.

B. REFER to Cruise Control Testing and Inspection for further diagnosis of the Clutch Pedal Position (CPP) switch.

C. REFER to Vehicle Dynamic Systems Testing and Inspection for further diagnosis of the ABS system and the CAN communication network.

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