Pinpoint Test U: Four-Wheel Drive (4WD) System Functional Test
Four Wheel Drive (4WD) Systems - 2-Speed Torque-On-Demand
Pinpoint Test U: Four-Wheel Drive (4WD) System Functional Test
Refer to Wiring Diagram Set 34, Four-Wheel Drive System for schematic and connector information Electrical Diagrams.
Normal Operation
When operating in 4WD (Four-Wheel Drive), the transfer case and both Integrated Wheel Ends (IWEs) are locked. When in 4L mode, the transfer case low range gear set provides an additional 2.64 gear reduction. When operating in 2H mode, the transfer case and both IWEs (Integrated Wheel Ends) are unlocked.
This pinpoint test is intended to diagnose the following:
- Transfer case and related components
- IWEs (Integrated Wheel Ends) and related components
- Wheel/tire assemblies
PINPOINT TEST U : Four-Wheel Drive (4WD) SYSTEM FUNCTIONAL TEST
NOTE: 4X4 is not intended for driving on hard/dry surfaces; using 4X4 mode while driving on these surfaces may produce noises like intermittent clunking, but will not damage driveline components.
U1 CHECK 2H MODE OPERATION
- Shift the transmission into the NEUTRAL position.
- Switch the Mode Select Switch (MSS) to 2H mode.
Are there any 4WD (Four-Wheel Drive) mode indicators present in the Instrument Cluster (IC) message center?
Yes
GO to U2.
No
GO to U4.
U2 CHECK FOR TCCM (Transfer Case Control Module) DTCs
- Shift the transmission into the PARK position.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Self-Test- TCCM (Transfer Case Control Module).
Are DTCs retrieved?
Yes
REFER to the Transfer Case Control Module (TCCM) DTC Chart for diagnosis. Four Wheel Drive (4WD) Systems - 2-Speed Torque-on-Demand
No
GO to U3.
U3 CHECK FOR WIND-UP IN 2H MODE
- Drive the vehicle on a dry, hard surface while executing turns.
Is wind-up present in turns?
Yes
GO to Pinpoint Test P. Pinpoint Test P: The Vehicle Does Not Shift Between 4H (4X4) and 4L (4X4 Low) Modes Correctly
No
GO to Pinpoint Test V. Pinpoint Test V: The 4X4 Mode Indicators Do Not Operate Correctly/Do Not Operate
U4 CHECK AUTO MODE OPERATION
- Switch the MSS (Mode Select Switch) to 4A mode.
Is the 4X4 auto (4A) mode indicator on in the IC (Instrument Cluster) message center?
Yes
GO to U7.
No
GO to U5.
U5 CHECK FOR DTCs
- Ignition ON.
- 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 - 2-Speed Torque-on-Demand
No
GO to U6.
U6 CHECK FOR WIND-UP IN 4A MODE
- Drive the vehicle on a dry, hard surface, executing turns while applying the throttle.
Is wind-up present in turns?
Yes
GO to U7.
No
GO to U8.
U7 CHECK THE 4WD (Four-Wheel Drive) PWM (Pulse-Width Modulation) CLUTCH STATUS (4WD_CLTCH_OUT) PID
- Enter the following diagnostic mode on the scan tool: DataLogger- TCCM (Transfer Case Control Module).
- Monitor the 4WD_CLTCH_OUT PID.
Does the PID indicate 2 to 10% clutch application at closed throttle?
Yes
GO to U8.
No
GO to U9.
U8 CHECK FOR WIND-UP IN 4A MODE WITH 100% CLUTCH USING THE 4WD (Four-Wheel Drive) PWM (Pulse-Width Modulation) CLUTCH STATUS (4WD_CLTCH_OUT) ACTIVE COMMAND
- Enter the following diagnostic mode on the scan tool: DataLogger- TCCM (Transfer Case Control Module).
- Command the 4WD_CLTCH_OUT to 100%.
- Drive the vehicle on a dry, hard surface, executing turns.
Is wind-up present in turns?
Yes
GO to U9.
No
CHECK the transfer case.
U9 CHECK AVERAGE FRONT WHEEL SPEED (FRT_WHL_SPD) AND AVERAGE REAR WHEEL SPEED (REAR_WHL_SPD) PIDs
- Enter the following diagnostic mode on the scan tool: DataLogger- TCCM (Transfer Case Control Module).
- Monitor the FRT_WHL_SPD and REAR_WHL_SPD PIDs.
- Drive the vehicle 30 km/h (18 mph).
- Record and compare the FRT_WHL_SPD and REAR_WHL_SPD PIDs.
Do the FRT_WHL_SPD and REAR_WHL_SPD PID values match within 1.5 km/h (1 mph)?
Yes
GO to U10.
No
VERIFY all 4 tires are the same size and brand. INSTALL new tires as necessary. If the tires are OK, CHECK the ABS and VERIFY that the 4 road tire sizes match. TEST the system for normal operation.
U10 CHECK THE ABSOLUTE THROTTLE POSITION (TP_TCCM) PID
- Enter the following diagnostic mode on the scan tool: DataLogger- TCCM (Transfer Case Control Module).
- Ignition ON.
- Monitor the TP_TCCM PID.
- NOTE: The TP_TCCM PID is Accelerator Pedal Position (APP) as communicated by the PCM via High Speed Controller Area Network (HS-CAN).
Slowly move throttle from closed throttle to Wide Open Throttle (WOT) and observe the TP_TCCM PID.
Does the TP_TCCM PID value vary between 0% at closed throttle and 100% at WOT (Wide Open Throttle)?
Yes
GO to U11.
No
CHECK the APP (Accelerator Pedal Position) sensor and/or the PCM. REFER to Computers and Control Systems Information.
U11 CHECK 4H MODE OPERATION
- Switch the MSS (Mode Select Switch) to 4H mode.
Does the 4X4 (4H) indicator illuminate in the IC (Instrument Cluster) message center correctly?
Yes
GO to U14.
No
GO to U12.
U12 CHECK FOR 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 retrieved?
Yes
REFER to the Transfer Case Control Module (TCCM) DTC Chart for diagnosis. Four Wheel Drive (4WD) Systems - 2-Speed Torque-on-Demand
No
GO to U13.
U13 CHECK FOR WIND-UP IN 4H MODE
- Drive the vehicle on a dry, hard surface while executing turns.
Is wind-up present in turns?
Yes
GO to Pinpoint Test Q. Pinpoint Test Q: Four-Wheel Drive (4WD) Does Not Engage At Speed Correctly
No
GO to Pinpoint Test O. Pinpoint Test O: The Vehicle Does Not Shift Between 4A (4X4 AUTO) and 4H (4X4) Modes Correctly
U14 CHECK FOR STRAIGHTLINE WIND-UP IN 4H MODE
- Drive the vehicle on a dry, hard surface.
Is straightline wind-up present?
Yes
GO to Pinpoint Test S. Pinpoint Test S: Vehicle Pulsates Or Shudders in a Straight Line (Straightline Driveline Wind-up)
No
GO to U15.
U15 CHECK WIND-UP IN TURNS IN 4H MODE
- Drive the vehicle in 4H mode while turning.
Is wind-up present in turns?
Yes
GO to U16.
No
GO to Pinpoint Test O. Pinpoint Test O: The Vehicle Does Not Shift Between 4A (4X4 AUTO) and 4H (4X4) Modes Correctly
U16 CHECK 4L MODE OPERATION
- Bring the vehicle to a stop with the transmission in NEUTRAL, switch the MSS (Mode Select Switch) to 4L mode.
Does the 4WD (Four-Wheel Drive) LOW (4L) indicator in the IC (Instrument Cluster) message center illuminate correctly?
Yes
GO to U19.
No
GO to U17.
U17 CHECK FOR 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 retrieved?
Yes
REFER to the Transfer Case Control Module (TCCM) DTC Chart for diagnosis. Four Wheel Drive (4WD) Systems - 2-Speed Torque-on-Demand
No
GO to U18.
U18 CHECK FOR WIND-UP IN 4L MODE
- Drive the vehicle on a dry, hard surface while executing turns.
Is wind-up present in turns?
Yes
GO to Pinpoint Test V. Pinpoint Test V: The 4X4 Mode Indicators Do Not Operate Correctly/Do Not Operate
No
GO to Pinpoint Test P. Pinpoint Test P: The Vehicle Does Not Shift Between 4H (4X4) and 4L (4X4 Low) Modes Correctly
U19 CHECK FOR WIND-UP IN TURNS IN 4L MODE
- Drive the vehicle on a dry, hard surface while executing turns.
Is wind-up present and 4L mode functioning?
Yes
GO to U20.
No
CHECK for TCCM (Transfer Case Control Module) DTCs. REFER to the Inspection and Verification procedure. Four Wheel Drive (4WD) Systems - 2-Speed Torque-on-Demand If no DTCs are present, GO to Pinpoint Test P. Pinpoint Test P: The Vehicle Does Not Shift Between 4H (4X4) and 4L (4X4 Low) Modes Correctly
U20 CHECK 4L MODE TO 2H MODE SHIFT
- With the vehicle at a stop and transmission in NEUTRAL, switch the MSS (Mode Select Switch) from 4L mode to 2H mode.
Are there any 4WD (Four-Wheel Drive) mode indicators present in the IC (Instrument Cluster) message center?
Yes
GO to U21.
No
GO to U23.
U21 CHECK FOR DTCs
- Shift the transmission into the PARK position.
- Release the brake pedal.
- Enter the following diagnostic mode on the scan tool: Self-Test- TCCM (Transfer Case Control Module).
Are DTCs retrieved?
Yes
REFER to the Transfer Case Control Module (TCCM) DTC Chart for diagnosis. Four Wheel Drive (4WD) Systems - 2-Speed Torque-on-Demand
No
GO to U22.
U22 CHECK FOR WIND-UP IN 2H MODE
- Drive the vehicle on a dry, hard surface while executing turns.
Is wind-up present in turns?
Yes
GO to Pinpoint Test P. Pinpoint Test P: The Vehicle Does Not Shift Between 4H (4X4) and 4L (4X4 Low) Modes Correctly
No
GO to Pinpoint Test V. Pinpoint Test V: The 4X4 Mode Indicators Do Not Operate Correctly/Do Not Operate
U23 CHECK FOR TRANSFER CASE DISENGAGEMENT
- With the vehicle in NEUTRAL, position it on a hoist.
- Rotate the rear driveshaft while observing the front driveshaft.
Does the front driveshaft rotate?
Yes
REFER to Transfer Case.
No
GO to U24.
U24 CHECK FOR LH AND RH IWE (Integrated Wheel End) DISENGAGEMENT
NOTE: The engine must be at idle during the following steps to supply vacuum for IWE (Integrated Wheel End) engagement/disengagement.
- Start the engine and allow to idle.
- Rotate the LF tire one revolution forward and one revolution backward while observing the LF halfshaft and U-joint.
- Rotate the RF tire one revolution forward and one revolution backward while observing the RF halfshaft and U-joint.
Does the LH or RH front halfshaft rotate?
Yes
GO to Pinpoint Test N. Pinpoint Test N: The Front Axle Does Not Engage/Disengage Correctly
No
GO to U25.
U25 CHECK FOR IWE (Integrated Wheel End) VACUUM LEAKS
- Ignition OFF.
- Disconnect both vacuum lines from the IWE (Integrated Wheel End) solenoid.
- Using a hand vacuum pump, apply 508 mm (20 in) Hg of vacuum to the IWE (Integrated Wheel End) apply vacuum circuit.
- Observe the vacuum reading.
Did the vacuum drop more than 25 mm (1 in) Hg per minute?
Yes
CHECK the IWE (Integrated Wheel End) and related components for leaks. GO to Pinpoint Test N. Pinpoint Test N: The Front Axle Does Not Engage/Disengage Correctly
No
GO to U26.
U26 CHECK 2H MODE TO 4H MODE SHIFT AT SPEED ABOVE 32 KM/H (20 MPH)
- Switch the MSS (Mode Select Switch) to 2H mode.
- Drive the vehicle on the road and shift from 2H mode to 4H mode while driving above 32 km/h (20 mph).
Does the transfer case shift to 4H mode satisfactorily?
Yes
The 4WD (Four-Wheel Drive) system is functioning correctly.
No
GO to Pinpoint Test Q. Pinpoint Test Q: Four-Wheel Drive (4WD) Does Not Engage At Speed Correctly