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Pinpoint Test A: The Pcm Does Not Respond To The Scan Tool

WARNING: This page is about a different car, the 2008 Mercury Milan, 2008 Lincoln MKZ, and 2008 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
  1. A1 POWERTRAIN CONTROL/EMISSIONS DIAGNOSIS (PC/ED) MANUAL PINPOINT TEST QA VERIFICATION CHECK 
    • Verify that the PC/ED pinpoint test QA has been performed.
    • Has the PC/ED pinpoint test QA been performed? 
    1. YES  : Go to  A2.
    2. NO  : REFER to Introduction - Gasoline Engines article, pinpoint test QA, to diagnose no communication with the PCM.
  2. A2 CHECK THE HS-CAN TERMINATION RESISTANCE 
    • Key in OFF position.
      • NOTE: Failure to disconnect the battery will result in false resistance readings.
    • Disconnect the battery ground cable.
      • Fig 1: Checking HS-CAN Termination Resistance
      GF0004695Courtesy of FORD MOTOR CO.
    • Measure the resistance between the DLC C251-6, circuit VDB04 (WH/BU), harness side and the DLC C251-14, circuit VDB05 (WH), harness side.
    • Is the resistance between 54 and 66 ohms? 
    1. YES  : Go to  A4.
    2. NO  : Go to  A3.
  3. A3 CHECK THE HS-CAN CIRCUITS BETWEEN THE DLC AND THE PCM FOR AN OPEN 
    • Disconnect: PCM C175b
      • Fig 2: Checking HS-CAN (+) Circuit
      GF0004696Courtesy of FORD MOTOR CO.
    • Measure the resistance between the PCM C175b-2, circuit VDB04 (WH/BU), harness side and the DLC C251-6, circuit VDB04 (WH/BU), harness side.
      • Fig 3: Checking HS-CAN (-) Circuit
      GF0004697Courtesy of FORD MOTOR CO.
    • Measure the resistance between the PCM C175b-3, circuit VDB05 (WH), harness side and the DLC C251-14, circuit VDB05 (WH), harness side.
    • Are the resistances less than 5 ohms? 
    1. YES  : Go to  A4.
    2. NO  : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
  4. A4 CHECK FOR CORRECT PCM OPERATION 
    • Disconnect all the PCM connectors.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect all the PCM connectors and make sure they seat correctly.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    1. YES  : INSTALL a new PCM. REFER to ELECTRONIC ENGINE CONTROLS - 2.3L article, ELECTRONIC ENGINE CONTROLS - 3.0L (4V) article or ELECTRONIC ENGINE CONTROLS - 3.5L article. CONNECT all modules. CONNECT the battery ground cable. 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. CONNECT all modules. CONNECT the battery ground cable. CLEAR the DTCs. REPEAT the network test with the scan tool.
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