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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 >> Inspection and Verification

Inspection and Verification

WARNING: This page is about a different variant/trim than selected.
  1. Verify the customer concern.
  2. Visually inspect for obvious signs of mechanical or electrical damage.
    VISUAL INSPECTION CHART

    Mechanical Electrical
    • Halfshafts
    • Integrated Wheel End (IWE)
    • Shift motor
    • Driveshaft and U-joints
    • Vacuum leaks
    • Fluid leaks
    • Matching tire sizes
    • Transfer case
    • Power Distribution Box (PDB) fuses:
      • 35 (20A)
      • 43 (20A)
      • 75 (5A)
    • Smart Junction Box (SJB) mini fuse 35 (10A)
    • Wiring harness
    • Mode Select Switch (MSS)
    • Synchronization clutch
    • Connector(s)
    • IWE vacuum solenoid
    • Circuitry
  3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
    4. NOTE: Make sure to use the latest scan tool software release.
  4. If the cause is not visually evident, connect the scan tool to the Data Link Connector (DLC).
    5. NOTE: The Vehicle Communication Module (VCM) LED prove out confirms power and ground from the DLC are provided to the VCM.
  5. If the scan tool does not communicate with the VCM:
    • check the VCM connection to the vehicle.
    • check the scan tool connection to the VCM.
    • refer to MODULE COMMUNICATIONS NETWORK article, No Power To The Scan Tool, to diagnose no power to the scan tool.
    6. NOTE: Before carrying out the self-test, make sure that:
    • ignition is in RUN.
    • 4A mode is selected (or the last mode selected before starting the self-test).
  6. If the scan tool does not communicate with the vehicle:
  7. Carry out the network test.
    • If the scan tool responds with no communication for one or more modules, refer to MODULE COMMUNICATIONS NETWORK article.
    • If the network test passes, retrieve and record continuous memory DTCs.
  8. Clear the DTCs and carry out the self-test diagnostics for the 4X4 control module.
  9. If the DTCs retrieved are related to the concern, go to the 4X4 Control Module DTC Chart. For all other DTCs, refer to MULTIFUNCTION ELECTRONIC MODULES article.
  10. If no DTCs related to the concern are retrieved, go to Symptom Chart - Four Wheel Drive (4WD)  or Go to Symptom Chart - NVH .
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