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Inspection and Verification

WARNING: This page is about a different car, the 2007 Mercury Mariner and 2007 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
  1. Verify the customer concern.
  2. Visually inspect the following for obvious signs of electrical damage.
    VISUAL INSPECTION CHART

    Electrical
    • Battery junction box (BJB) fuse(s):
      • 4 (5A) (no communication with powertrain control module [PCM])
      • 11 (10A) (no communication with PCM)
      • 15 (30A) (no communication with anti-lock brake system [ABS] module)
    • Smart junction box (SJB) fuse(s):
      • 4 (10A) (no communication with the smart junction box [SJB])
      • 6 (15A) (no communication with the SJB)
      • 7 (10A) (no communication with instrument cluster, no power to scan tool)
      • 17 (15A) (no communication with SJB)
      • 18 (10A) (no communication with four wheel drive [4WD] control module)
      • 22 (10A) (no communication with instrument cluster)
      • 28 (10A) (no communication with instrument cluster)
      • 29 (10A) (no communication with parking aid module)
      • 33 (15A) (no communication with restraints control module [RCM])
      • 34 (5A) (no communication with ABS module)
      • 35 (5A) (no communication with 4WD control module)
    • Data link connector (DLC)
    • Wiring harness
    • 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.
    NOTE: The vehicle communication module (VCM) LED prove-out confirms power and ground from the DLC are provided to the VCM.
  4. If the cause is not visually evident, connect the scan tool to the DLC.

    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.
    • Go to Pinpoint Test J , to diagnose no power to the scan tool.
    5. NOTE: During the network test, the scan tool will first attempt to communicate with the PCM, after establishing communication with the PCM, the scan tool will then attempt to communicate with all other modules on the vehicle.
  5. Carry out the network test:
    • If the network test passes, retrieve and record the continuous memory DTCs and proceed to Step 6.
    • If the network test fails, go to Symptom Chart  to identify the module not communicating.
  6. If the DTCs retrieved are related to the concern, go to the Communication Network Diagnostic Trouble Code (DTC) Index. For all other DTCs, refer to MULTIFUNCTION ELECTRONIC MODULES article.
  7. If no DTCs related to the concern are retrieved, go to Symptom Chart .
NOTE: DTC U1900 will set in a module that is reporting a communication fault from another module on the data bus. The module that reports the fault is not the problem module.
COMMUNICATION NETWORK DIAGNOSTIC TROUBLE CODES (DTC) INDEX

DTC Description Source Action
U0073 Control Module Communication Bus Off Smart junction box (SJB) The module could not communicate on the network at a point in time. The fault is not currently present. CLEAR the DTC. REPEAT the network test with the scan tool.
U0101 Lost Communication With TCM Powertrain control module (PCM) CLEAR the DTC. REPEAT the network test with the scan tool. FOLLOW the appropriate pinpoint test for the module which fails the network test.
U0121 Lost Communication With Anti-Lock Brake System (ABS) Control Module Four wheel drive (4WD) control module CLEAR the DTC. REPEAT the network test with the scan tool. FOLLOW the appropriate pinpoint test for the module which fails the network test.
U0129 Lost Communication With Brake System Control Module PCM CLEAR the DTC. REPEAT the network test with the scan tool. FOLLOW the appropriate pinpoint test for the module which fails the network test.
U0155 Lost Communication With Instrument Panel Cluster (IC) Control Module PCM CLEAR the DTC. REPEAT the network test with the scan tool. FOLLOW the appropriate pinpoint test for the module which fails the network test.
U1900 CAN Communication Bus Fault-Receive Error Anti-lock brake system (ABS) module For module that failed the network test, go to Symptom Chart .
U1900 CAN Communication Bus Fault-Receive Error Instrument cluster For module that failed the network test, go to Symptom Chart .
U1900 CAN Communication Bus Fault-Receive Error SJB For module that failed the network test, go to Symptom Chart .
U1900 CAN Communication Bus Fault-Receive Error 4WD control module For module that failed the network test, go to Symptom Chart .
U2023 Fault Received From External Node ABS module RETRIEVE and FOLLOW non-network DTCs from other modules. REFER to MULTIFUNCTION ELECTRONIC MODULES article.
U2023 Fault Received From External Node SJB RETRIEVE and FOLLOW non-network DTCs from other modules. REFER to MULTIFUNCTION ELECTRONIC MODULES article.
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