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Home >> Ford >> 2008 >> Expedition EL RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 1 (Four Wheel Drive (4WD) Systems) >> Diagnostic Tests >> Four Wheel Drive (4WD) Systems - 2-Speed Torque-On-Demand >> Pinpoint Tests >> Pinpoint Test U: Four-Wheel Drive (4WD) System Functional Test >> PINPOINT TEST U: Four-Wheel Drive (4WD) SYSTEM FUNCTIONAL TEST

PINPOINT TEST U: Four-Wheel Drive (4WD) SYSTEM FUNCTIONAL TEST

WARNING: This page is about a different variant/trim than selected.
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.
  1. 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? 
    1. YES  : Go to  U2.
    2. NO  : Go to  U4.
  2. U2 CHECK FOR DTCs 
    • Shift the transmission into the PARK position.
    • Connect the diagnostic tool.
    • Carry out the 4X4 control module on-demand self test.
    • Are DTCs retrieved? 
    1. YES  : REFER to the 4X4 Control Module DTC Chart for diagnosis.
    2. NO  : Go to  U3.
  3. 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? 
    1. YES  : Go to Pinpoint Test P .
    2. NO  : Go to Pinpoint Test V .
  4. 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? 
    1. YES  : REPAIR the transfer case. REFER to TRANSFER CASE article.
    2. NO  : Go to  U5.
  5. U5 CHECK AUTO MODE OPERATION 
    • Switch the MSS to 4A mode.
    • Is the 4X4 auto (4A) mode indicator ON in the IC message center? 
    1. YES  : Go to  U8.
    2. NO  : Go to  U6.
  6. U6 CHECK FOR DTCs 
    • Connect the diagnostic tool.
    • Carry out the 4X4 control module on-demand self test.
    • Are DTCs present? 
    1. YES  : REFER to the 4X4 Control Module DTC Chart for diagnosis.
    2. NO  : Go to  U7.
  7. U7 CHECK FOR WIND-UP IN 4A MODE 
    • Drive the vehicle on a dry, hard surface in turns.
    • Is wind-up present in turns? 
    1. YES  : Go to  U8.
    2. NO  : Go to  U9.
  8. U8 CHECK THE 4WD CLUTCH PWM STATUS (4WDCPWMST) PID 
    • Enter the following diagnostic mode on the diagnostic tool: DataLogger - 4X4 Control Module
    • Monitor the 4WDCPWMST PID.
    • Does the 4WDCPWMST PID indicate at least 10% clutch application at closed throttle? 
    1. YES  : Go to  U9.
    2. NO  : Go to  U10.
  9. 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 diagnostic 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? 
    1. YES  : Go to  U10.
    2. NO  : CHECK the transfer case. REFER to TRANSFER CASE article.
  10. U10 CHECK FRONT SHAFT SPEED (FR_OUTSHA) AND REAR SHAFT SPEED (R_OUTSHA) PIDs 
    • Enter the following diagnostic mode on the diagnostic 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)? 
    1. YES  : Go to  U11.
    2. NO  : CHECK the ABS. REFER to VEHICLE DYNAMIC SYSTEMS article and VERIFY the 4 road tire sizes match.
  11. U11 CHECK THE THROTTLE POSITION STATUS (TPI) PID 
    • Enter the following diagnostic mode on the diagnostic 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? 
    1. YES  : Go to  U12.
    2. NO  : CHECK the APP sensor and/or the PCM. REFER to the Introduction - Gasoline Engines article.
  12. U12 CHECK 4H MODE OPERATION 
    • Switch the MSS to 4H mode.
    • Does the 4X4 (4H) indicator illuminate in the IC message center correctly? 
    1. YES  : Go to  U15.
    2. NO  : Go to  U13.
  13. U13 CHECK FOR DTCs 
    • Shift the transmission into the PARK position.
    • Connect the diagnostic tool.
    • Carry out the 4X4 control module on-demand self test.
    • Are DTCs retrieved? 
    1. YES  : REFER to the 4X4 Control Module DTC Chart for diagnosis.
    2. NO  : Go to  U14.
  14. 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? 
    1. YES  : Go to Pinpoint Test Q .
    2. NO  : Go to Pinpoint Test O .
  15. U15 CHECK FOR STRAIGHT-LINE WIND-UP IN 4H MODE 
    • Drive the vehicle on a dry, hard surface.
    • Is straightline wind-up present? 
    1. YES  : Go to Pinpoint Test S .
    2. NO  : Go to  U16.
  16. U16 CHECK WIND-UP IN TURNS IN 4H MODE 
    • Drive the vehicle in 4H mode while turning.
    • Is wind-up present in turns? 
    1. YES  : Go to  U17.
    2. NO  : Go to Pinpoint Test O .
  17. 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? 
    1. YES  : Go to  U20.
    2. NO  : Go to  U18.
  18. U18 CHECK FOR DTCs 
    • Shift the transmission into the PARK position.
    • Connect the diagnostic tool.
    • Carry out the 4X4 control module on-demand self test.
    • Are DTCs retrieved? 
    1. YES  : REFER to the 4X4 Control Module DTC Chart for diagnosis.
    2. NO  : Go to  U19.
  19. 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? 
    1. YES  : Go to Pinpoint Test V .
    2. NO  : Go to Pinpoint Test P .
  20. 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? 
    1. YES  : Go to  U21.
    2. NO  : CHECK for 4X4 control module DTCs. REFER to Inspection and Verification . If no DTCs are present, go to Pinpoint Test P .
  21. 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? 
    1. YES  : Go to  U22.
    2. NO  : Go to  U24.
  22. U22 CHECK FOR DTCs 
    • Shift the transmission into the PARK position.
    • Release the brake pedal.
    • Connect the diagnostic tool.
    • Carry out the 4X4 control module on-demand self test.
    • Are DTCs retrieved? 
    1. YES  : REFER to the 4X4 Control Module DTC Chart for diagnosis.
    2. NO  : Go to  U23.
  23. 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? 
    1. YES  : Go to Pinpoint Test P .
    2. NO  : Go to Pinpoint Test V .
  24. U24 CHECK FOR TRANSFER CASE DISENGAGEMENT 
    • With the vehicle in NEUTRAL, position it on a hoist. Refer to JACKING AND LIFTING article.
    • Rotate the rear driveshaft while observing the front driveshaft.
    • Does the front driveshaft rotate? 
    1. YES  : REFER to TRANSFER CASE article.
    2. NO  : Go to  U25.
  25. 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? 
    1. YES  : Go to Pinpoint Test N .
    2. NO  : Go to  U26.
  26. U26 CHECK FOR IWE VACUUM LEAKS 
    • Key in OFF position.
    • 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? 
    1. YES  : CHECK the IWE and related components for leaks. Go to Pinpoint Test N .
    2. NO  : Go to  U27.
  27. 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? 
    1. YES  : The 4WD system is functioning correctly.
    2. NO  : Go to Pinpoint Test Q .
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