Pinpoint Test U: Four-Wheel Drive (4WD) System Functional Test
Four Wheel Drive (4WD) Systems - 2-Speed Torque-On-Demand
Pinpoint Tests
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. Diagrams By Number
Normal Operation
When operating in Four-Wheel Drive (4WD), 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 are unlocked.
This pinpoint test is intended to diagnose the following:
- Transfer case and related components
- IWEs 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.
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U1 CHECK 2H MODE OPERATION
- Stop the vehicle.
- Shift the transmission into the NEUTRAL position.
- Switch the Mode Select Switch (MSS) to 2H mode.
- Are there any 4WD mode indicators present in the Instrument Cluster (IC) message center?
Yes
GO to U2.
No
GO to U4.
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U2 CHECK FOR DTCs
- Shift the transmission into the PARK position.
- Connect the scan tool.
- Carry out the 4X4 control module on-demand self-test.
- Are DTCs retrieved?
Yes
REFER to the 4X4 Control Module DTC Chart for diagnosis. Four Wheel Drive (4WD) Systems -2- Speed Torque-on-Demand
No
GO to U3.
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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
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U4 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
REPAIR the transfer case.
No
GO to U5.
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U5 CHECK AUTO MODE OPERATION
- Switch the MSS to 4A mode.
- Is the 4X4 auto (4A) mode indicator ON in the IC message center?
Yes
GO to U8.
No
GO to U6.
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U6 CHECK FOR DTCs
- Connect the scan tool.
- Carry out the 4X4 control module on-demand self-test.
- Are DTCs present?
Yes
REFER to the 4X4 Control Module DTC Chart for diagnosis. Four Wheel Drive (4WD) Systems -2- Speed Torque-on-Demand
No
GO to U7.
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U7 CHECK FOR WIND-UP IN 4A MODE
- Drive the vehicle on a dry, hard surface in turns.
- Is wind-up present in turns?
Yes
GO to U8.
No
GO to U9.
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U8 CHECK THE 4WD CLUTCH PWM STATUS (4WDCPWMST) PID
- Enter the following diagnostic mode on the scan tool: DataLogger - 4X4 Control Module.
- Monitor the 4WDCPWMST PID.
- Does the 4WDCPWMST PID indicate at least 10% clutch application at closed throttle?
Yes
GO to U9.
No
GO to U10.
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U9 CHECK FOR WIND-UP IN 4A WITH 100% CLUTCH USING PWM OUTPUT CONTROL COMMAND #1 (CLCH_SOL) ACTIVE COMMAND
- Enter the following diagnostic mode on the scan tool: DataLogger - 4X4 Control Module.
- Using the CLCH_SOL active command, command the clutch duty cycle to 100%.
- Drive the vehicle on a dry, hard surface in turns.
- Is wind-up present in turns?
Yes
GO to U10.
No
CHECK the transfer case.
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U10 CHECK FRONT SHAFT SPEED (FR_OUTSHA) AND REAR SHAFT SPEED (R_OUTSHA) PIDs
- Enter the following diagnostic mode on the scan tool: DataLogger - 4X4 Control Module.
- Monitor the FR_OUTSHA AND R_OUTSHA PIDs.
- Drive the vehicle at 30 km/h (18 mph).
- Record and compare the FR_OUTSHA AND R_OUTSHA PIDs.
- Do the FR_OUTSHA and R_OUTSHA PID values match within 1.5 km/h (1 mph)?
Yes
GO to U11.
No
CHECK the ABS. VERIFY the 4 road tire sizes match.
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U11 CHECK THE THROTTLE POSITION STATUS (TPI) PID
- Enter the following diagnostic mode on the scan tool: DataLogger - 4X4 Control Module.
- Monitor the TPI PID from the 4X4 control module.
- Key ON Engine OFF (KOEO).
- NOTE: The TPI 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 4X4 control module TPI PID.
- Does the TPI PID value vary between 0 at closed throttle and 255 at WOT?
Yes
GO to U12.
No
CHECK the APP sensor and/or the PCM. REFER to Computers and Control Systems Information.
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U12 CHECK 4H MODE OPERATION
- Switch the MSS to 4H mode.
- Does the 4X4 (4H) indicator illuminate in the IC message center correctly?
Yes
GO to U15.
No
GO to U13.
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U13 CHECK FOR DTCs
- Shift the transmission into the PARK position.
- Connect the scan tool.
- Carry out the 4X4 control module on-demand self-test.
- Are DTCs retrieved?
Yes
REFER to the 4X4 Control Module DTC Chart for diagnosis. Four Wheel Drive (4WD) Systems -2- Speed Torque-on-Demand
No
GO to U14.
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U14 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: 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
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U15 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: Straightline Driveline Wind-Up
No
GO to U16.
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U16 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 U17.
No
Go To Pinpoint Test O. Pinpoint Test O: the Vehicle Does Not Shift Between 4A (4X4 Auto) and 4H (4X4) Modes Correctly
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U17 CHECK 4L MODE OPERATION
- Bring the vehicle to a stop with the transmission in NEUTRAL, switch the MSS to 4L mode.
- Does the 4WD LOW (4L) indicator in the IC message center illuminate correctly?
Yes
GO to U20.
No
GO to U18.
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U18 CHECK FOR DTCs
- Shift the transmission into the PARK position.
- Connect the scan tool.
- Carry out the 4X4 control module on-demand self-test.
- Are DTCs retrieved?
Yes
REFER to the 4X4 Control Module DTC Chart for diagnosis. Four Wheel Drive (4WD) Systems -2- Speed Torque-on-Demand
No
GO to U19.
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U19 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
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U20 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 U21.
No
CHECK for 4X4 control module DTCs. REFER to the Inspection and Verification procedure. 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
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U21 CHECK 4L MODE TO 2H MODE SHIFT
- With the vehicle at a stop and transmission in NEUTRAL, switch the MSS from 4L mode to 2H mode.
- Are there any 4WD mode indicators present in the IC message center?
Yes
GO to U22.
No
GO to U24.
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U22 CHECK FOR DTCs
- Shift the transmission into the PARK position.
- Release the brake pedal.
- Connect the scan tool.
- Carry out the 4X4 control module on-demand self-test.
- Are DTCs retrieved?
Yes
REFER to the 4X4 Control Module DTC Chart for diagnosis. Four Wheel Drive (4WD) Systems -2- Speed Torque-on-Demand
No
GO to U23.
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U23 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
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U24 CHECK FOR TRANSFER CASE DISENGAGEMENT
- With the vehicle in NEUTRAL, position it on a hoist. Refer to Maintenance/Service and Repair.
- Rotate the rear driveshaft while observing the front driveshaft.
- Does the front driveshaft rotate?
Yes
REFER to Transfer Case.
No
GO to U25.
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U25 CHECK FOR LH AND RH IWE DISENGAGEMENT
NOTE: The engine must be at idle during the following steps to supply vacuum for IWE 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 U26.
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U26 CHECK FOR IWE VACUUM LEAKS
- Ignition OFF.
- Disconnect both vacuum lines from the IWE solenoid.
- Using a hand vacuum pump, apply 508 mm (20 in) Hg of vacuum to the IWE apply vacuum circuit.
- Observe the vacuum reading.
- Did the vacuum drop more than 25 mm (1 in) Hg per minute?
Yes
CHECK the IWE and related components for leaks. Go To Pinpoint Test N. Pinpoint Test N: the Front Axle Does Not Engage/Disengage Correctly
No
GO to U27.
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U27 CHECK 2H MODE TO 4H MODE SHIFT AT SPEED ABOVE 32 KM/H (20 MPH)
- Switch the MSS 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 system is functioning correctly.
No
Go To Pinpoint Test Q. Pinpoint Test Q: 4WD Does Not Engage at Speed Correctly
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