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Pinpoint Test B : P0645

NOTE: Use the correct probe adapter(s) from the Flex Probe Kit when taking measurements. Failure to use the correct probe adapter(s) may damage the connector.

  1. B1 CHECK THE VOLTAGE TO THE A/C (AIR CONDITIONING) CLUTCH RELAY VOLTAGE SUPPLY CIRCUITS

    • Ignition OFF.

    • Disconnect A/C clutch relay.

    • Ignition ON.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      A/C clutch relay socket 1
      GFD389390Courtesy of FORD MOTOR COMPANY
      		 Ground
      A/C clutch relay socket 3
      GFD389390Courtesy of FORD MOTOR COMPANY
      		 Ground

    Are the voltages greater than 11 volts? 

    Yes  GO to  B2
    No  VERIFY BJB fuses 42 (15A) and 23 (10A) are OK. If not OK, REFER to the OEM ELECTRICAL WIRING DIAGRAM INTRODUCTION to identify the possible causes of the circuit short. If OK, REPAIR the circuit.

  2. B2 CHECK THE A/C (AIR CONDITIONING) CLUTCH RELAY

    • Carry out the component test on the A/C clutch relay. Refer to the appropriate Wiring Diagrams for schematic and connector information.

    Did the relay pass the component test? 

    Yes  GO to  B3
    No  INSTALL a new A/C clutch relay.

  3. B3 CHECK THE A/C (AIR CONDITIONING) CLUTCH RELAY CONTROL CIRCUIT FOR A SHORT TO VOLTAGE

    • Ignition OFF.

    • Disconnect PCM, 2. 3L C1551B or 5. 0L C175B, or 5. 2L C1381B.

    • Ignition ON.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      A/C clutch relay socket 2
      GFD389390Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is any voltage present? 

    Yes  REPAIR the circuit.
    No  GO to  B4

  4. B4 CHECK THE A/C (AIR CONDITIONING) CLUTCH RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND

    • Ignition OFF.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      A/C clutch relay socket 2
      GFD389391Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the resistance greater than 10, 000 ohms? 

    Yes  GO to  B5
    No  REPAIR the circuit.

  5. B5 CHECK THE A/C (AIR CONDITIONING) CLUTCH RELAY CONTROL CIRCUIT FOR AN OPEN

    • Measure:

      2. 3L 

      Positive Lead Measurement / Action Negative Lead
      A/C clutch relay socket 2
      GFD389391Courtesy of FORD MOTOR COMPANY
      		 C1551B-62

      5. 0L 

      Positive Lead Measurement / Action Negative Lead
      A/C clutch relay socket 2
      GFD389391Courtesy of FORD MOTOR COMPANY
      		 C175B-19

      5. 2L 

      Positive Lead Measurement / Action Negative Lead
      A/C clutch relay socket 2
      GFD389391Courtesy of FORD MOTOR COMPANY
      		 C1381B-15

    Is the resistance less than 3 ohms? 

    Yes  GO to  B6
    No  REPAIR the circuit.

  6. B6 CHECK FOR CORRECT PCM (POWERTRAIN CONTROL MODULE) OPERATION

    • Ignition OFF.

    • Disconnect and inspect all PCM connectors.

    • Repair:

      • corrosion (install new connector or terminals - clean module pins)
      • damaged or bent pins - install new terminals/pins
      • pushed-out pins - install new pins as necessary

    • Reconnect all PCM connectors. Make sure they seat and latch correctly.

    • Operate the system and determine if the concern is still present.

    Is the concern still present? 

    Yes  CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, Refer to PCM GUIDED ROUTINE .
    No  The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.
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