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Pinpoint Test H: The Transmission Control Module (TCM) Does Not Respond To The Scan Tool

WARNING: This page is about a different car, the 2008 Mercury Mariner and 2008 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
  1. H1 CHECK THE POWER TO THE TCM 
    • Key in OFF position.
    • Disconnect: TCM C1458a
    • Key in ON position.
    • Measure the voltage between the TCM, harness side and ground as follows:
      Connector-Pin Circuit
      C1458a-4 CBB27 (GN/BN)
      C1458a-5 CBB27 (GN/BN)
      C1458a-12 SBB08 (VT/RD)
    • Are the voltages greater than 10 volts? 
    1. YES  : Go to  H2.
    2. NO  : VERIFY the battery junction box (BJB) fuse 27 (10A) or fuse 8 (5A) is OK. If OK, REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
  2. H2 CHECK THE TCM GROUNDS 
    • Key in OFF position.
    • Measure the resistance between the TCM harness side and ground as follows:
      Connector-Pin Circuit
      C1458a-2 GD121 (BK/YE)
      C1458a-8 GD121 (BK/YE)
    • Are the resistances less than 5 ohms? 
    1. YES  : Go to  H3.
    2. NO  : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
  3. H3 CHECK THE HS-CAN CIRCUITS BETWEEN THE TCM AND THE DATA LINK CONNECTOR (DLC) FOR AN OPEN 
    • Measure the resistance between the TCM C1458a-1, circuit VDB04 (WH/BU), harness side and the DLC C251-6, circuit VDB04 (WH/BU), harness side; and between the TCM C1458a-7, circuit VDB05 (WH), harness side and the DLC C251-14, circuit VDB05 (WH), harness side.
      • Fig 1: Checking Circuits For Open
      GF0026051Courtesy of FORD MOTOR CO.
    • Are the resistances less than 5 ohms? 
    1. YES  : Go to  H4.
    2. NO  : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
  4. H4 CHECK FOR CORRECT TCM OPERATION 
    • Disconnect the TCM connector.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect the TCM connector and make sure it seats correctly.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    1. YES  : INSTALL a new TCM. REFER to AUTOMATIC TRANSAXLE/TRANSMISSION - ELECTRONICALLY CONTROLLED CONTINUOUSLY VARIABLE TRANSMISSION (ECVT) article. CLEAR the DTCs. REPEAT the network test with the scan tool.
    2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
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