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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 Sable, 2008 Ford Taurus X, and 2008 Ford Taurus. 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.
NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the Pinpoint Test.
  1. A1 CHECK THE DATA LINK CONNECTOR (DLC) PINS FOR DAMAGE 
    • Key in OFF position.
    • Disconnect the scan tool cable from the DLC.
    • Inspect DLC pins 6 and 14 for damage.
      • Fig 1: Checking Data Link Connector (DLC) Pins For Damage
      GF0004716Courtesy of FORD MOTOR CO.
    • Are DLC pins 6 and 14 OK? 
    1. YES  : Go to  A2.
    2. NO  : REPAIR the DLC as necessary. CLEAR the DTCs. REPEAT the network test with the scan tool.
  2. A2 POWERTRAIN CONTROL/EMISSIONS DIAGNOSIS (PC/ED) PINPOINT TEST QA VERIFICATION 
    • Verify that PC/ED pinpoint test QA has been carried out.
    • Has pinpoint test QA been carried out? 
    1. YES  : Go to  A3.
    2. NO  : REFER to the Introduction - Gasoline Engines article, pinpoint test QA to diagnose no communication with the PCM.
  3. A3 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.
    • Disconnect the scan tool from the DLC.
    • Measure the resistance between the DLC C251-6, circuit VDB04 (WH/BU), harness side and the DLC C251-14, circuit VDB05 (WH), harness side.
      • Fig 2: Measuring Resistance
      GF0004695Courtesy of FORD MOTOR CO.
    • Is the resistance between 54 and 66 ohms? 
    1. YES  : Go to  A5.
    2. NO  : Go to  A4.
  4. A4 CHECK THE CAN CIRCUITS BETWEEN THE DLC AND THE PCM FOR AN OPEN  
    • Disconnect: PCM C175b
    • 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
      GF0004696Courtesy 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.
      • Fig 4: Checking HS-CAN (-) Circuit
      GF0004697Courtesy of FORD MOTOR CO.
    • Are the resistances less than 5 ohms? 
    1. YES  : Go to  A5.
    2. NO  : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
  5. A5 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 article. CONNECT all the modules. 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 the modules. CLEAR the DTCs. REPEAT the network test with the scan tool.
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