Pinpoint Test F: Four-Wheel Drive (4WD) System Jumps Out Of Gear

Four Wheel Drive (4WD) Systems - 1-Speed Torque-On-Demand

Pinpoint Test F: Four-Wheel Drive (4WD) System Jumps Out of Gear

Normal Operation

Once the Four-Wheel Drive (4WD) system engages the user selected mode, that mode should be maintained. If the 4WD (Four-Wheel Drive) system does not stay in the selected position, systematically check the 4WD (Four-Wheel Drive) system components.

This pinpoint test is intended to diagnose the following:

- Integrated Wheel End (IWE) vent line(s)

- Mode Select Switch (MSS)

- Transfer case

PINPOINT TEST F : THE 4WD (Four-Wheel Drive) SYSTEM JUMPS OUT OF GEAR

F1 CHECK FOR OBSTRUCTED IWE (Integrated Wheel End) VENT LINES

- With the vehicle in NEUTRAL, position in on a hoist.

- NOTE: The IWE (Integrated Wheel End) vent port is the smaller of the 2 vacuum ports.

Disconnect the LH IWE (Integrated Wheel End) line from the vent port.


- Attach a hand vacuum pump to the IWE (Integrated Wheel End) vent line.

- Attempt to draw and hold a vacuum.

- Connect LH IWE (Integrated Wheel End) line.

- Disconnect the RH IWE (Integrated Wheel End) line from the vent port.

- Attempt to draw and hold a vacuum.

Can a vacuum be held on either IWE (Integrated Wheel End) vent line?

Yes
INSTALL new IWE (Integrated Wheel End) vent lines as necessary. TEST the system for normal operation.

No
GO to F2.

F2 CHECK THE MSS (Mode Select Switch) SWITCH POSITION (4X4_SW) PID

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: DataLogger- TCCM (Transfer Case Control Module).

- Drive the vehicle.

- Dynamically monitor the 4X4_SW PID while driving the vehicle in each MSS (Mode Select Switch) position.

MSS (Mode Select Switch) Position PID Status 4X2 2WD 4X4 AUTO Automatic 4X4 4WD-HIGH

Does the PID always agree with the MSS (Mode Select Switch) position?

Yes
GO to F3.

No
GO to Pinpoint Test D. Pinpoint Test D: The Vehicle Does Not Shift Between 4X4 AUTO and 4X4 Modes Correctly

F3 CHECK THE 4WD (Four-Wheel Drive) INDICATORS

- Apply the brakes and stop the vehicle.

- Shift the transmission into the NEUTRAL position.

- NOTE: 2H is indicated by the absence of 4X4 AUTO, 4H or 4L mode indicators in the Instrument Cluster (IC) message center.

Observe the 4WD (Four-Wheel Drive) indicators in the Instrument Cluster (IC) while cycling through each MSS (Mode Select Switch) position.

Do the 4WD (Four-Wheel Drive) indicators match MSS (Mode Select Switch) switch positions?

Yes
GO to Pinpoint Test D. Pinpoint Test D: The Vehicle Does Not Shift Between 4X4 AUTO and 4X4 Modes Correctly

No
GO to F4.

F4 CHECK FOR TCCM (Transfer Case Control Module) DTCs

- Shift the transmission into the PARK position.

- Enter the following diagnostic mode on the scan tool: Self-Test- TCCM (Transfer Case Control Module).

Are DTCs present?

Yes
REFER to the Transfer Case Control Module (TCCM) DTC Chart for diagnosis. Four Wheel Drive (4WD) Systems - 1-Speed Torque-on-Demand

No
CHECK the transfer case fluid level. If the fluid level is OK, CHECK for internal transfer case faults. REFER to Transfer Case. TEST the system for normal operation.