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Pinpoint Test I: The BCM Does Not Respond To The Scan Tool

WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to BATTERY, MOUNTING AND CABLES .
  1. I1 CHECK THE POWER TO THE BCM 
    WARNING: To prevent the risk of high-voltage shock, always follow precisely all warnings and service instructions, including instructions to depower the system. The high-voltage hybrid system utilizes approximately 300 volts DC, provided through high-voltage cables to its components and modules. The high-voltage cables and wiring are identified by orange harness tape or orange wire covering. All high-voltage components are marked with high-voltage warning labels with a high-voltage symbol. Failure to follow these instructions may result in serious personal injury or death.
    WARNING: Always wear high-voltage insulated safety gloves with leather outer gloves and a face shield when servicing the battery pack sensor module (BPSM) and never remove the high-voltage BPSM connector unless directed by a service procedure. High voltage is present at the BPSM at all times, even with service disconnect plug removal  . Depowering the system will not remove voltage from the BPSM connector with the orange harness. Follow all service instructions. Failure to follow these instructions may result in serious personal injury or death.
    • Ignition OFF.
    • Disconnect: BCM  C4227a.
    • Ignition ON.
    • Measure the voltage between the BCM  , harness side and ground as follows:
      CONNECTOR-PIN REFERENCE CHART

      Connector-Pin Circuit
      C4227a-4 SBB15 (WH/RD)
      C4227a-5 SBB15 (WH/RD)
      C4227a-6 SBB15 (WH/RD)
      C4227a-10 SBB08 (VT/RD)
      C4227a-11 SBB08 (VT/RD)
      C4227a-14 CBB26 (BU/WH)
      C4227a-19 CBB25 (WH/OG)
      Fig 1: Measuring Voltage Between BCM, Harness Side And Ground
      G06390971Courtesy of FORD MOTOR CO.
    • Are the voltages greater than 10 volts? 
    • Yes:  GO to I2  .
    • No:  VERIFY the Battery Junction Box (BJB) fuses 8 (5A), 25 (5A), 26 (20A) and 15 (50A) are OK. If OK, REPAIR the circuit in question. If not OK, REFER to the appropriate SYSTEM WIRING DIAGRAMS article to identify the possible causes of the circuit short. CLEAR the DTCs. REPEAT the network test with the scan tool.
  2. I2 CHECK THE BCM GROUNDS 
    • Ignition OFF.
    • Disconnect: Negative Battery Cable.
    • Measure the resistance between the BCM  , harness side and ground as follows:
      CONNECTOR-PIN REFERENCE CHART

      Connector-Pin Circuit
      C4227a-30 GD182 (BK/GY)
      C4227a-31 GD182 (BK/GY)
      C4227a-35 GD149 (BK/GY)
      C4227a-36 GD149 (BK/GY)
      C4227a-37 GD149 (BK/GY)
      Fig 2: Measuring Resistance Between BCM, Harness Side And Ground
      G06390972Courtesy of FORD MOTOR CO.
    • Are the resistances less than 5 ohms? 
    • Yes:  GO to I3  .
    • No:  REPAIR the circuit in question. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.
  3. I3 CHECK THE HS-CAN CIRCUITS BETWEEN THE BCM AND THE DLC FOR AN OPEN 
    • Measure the resistance between the BCM  C4227a-29, circuit VDB04 (WH/BU), harness side and the DLC  C251-6, circuit VDB04 (WH/BU), harness side.
      Fig 3: Measuring Resistance Between BCM C4227A-29, Circuit VDB04 (WH/BU) And DLC C251-6, Circuit VDB04 (WH/BU), Harness Side
      G06099331Courtesy of FORD MOTOR CO.
    • Measure the resistance between the BCM  C4227a-28, circuit VDB05 (WH), harness side and the DLC  C251-14, circuit VDB05 (WH), harness side.
      Fig 4: Measuring Resistance Between BCM C4227A-28, Circuit VDB05 (WH) And DLC C251-14, Circuit VDB05 (WH), Harness Side
      G06099332Courtesy of FORD MOTOR CO.
    • Are the resistances less than 5 ohms? 
    • Yes:  CONNECT the negative battery cable. GO to I4  .
    • No:  REPAIR the circuit in question. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.
  4. I4 CHECK FOR CORRECT BCM OPERATION 
    NOTE: Do not disconnect the high-voltage cables or connectors in the following step.
    • Disconnect all the BCM  connectors.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect all the BCM  connectors and make they seat correctly.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    • Yes:  INSTALL a new High Voltage Traction Battery (HVTB). REFER to HIGH VOLTAGE TRACTION BATTERY . CLEAR the DTCs. REPEAT the network test with the scan tool.
    • No:  The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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