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Home >> Ford >> 2018 >> Taurus Limited, FWD, Gas >> Repair and Diagnosis >> External Pages >> Different car >> Section 32 (Climate Control System - General Information (2 Of 2)) >> Diagnosis And Testing >> Climate Control System - Vehicles With: Electronic Automatic Temperature Control (EATC) >> Pinpoint Tests >> Pinpoint Test B : P0645, P0646, P0647

Pinpoint Test B : P0645, P0646, P0647

WARNING: This page is about a different car, the 2018 Ford EcoSport. However, it is still accessible from the selected car via links, so may be relevant.
  1. Automatic Climate Control System for schematic and connector information.

    Normal Operation and Fault Conditions 

    Voltage is provided to the A/C clutch relay coil. When A/C is requested and A/C line pressures allow, a ground is provided to the A/C clutch relay coil from the PCM, energizing the A/C clutch relay.

    DTC Fault Trigger Conditions 

    DTC Description Fault Trigger Condition
    PCM P0645:00 A/C Clutch Relay Control Circuit: No Sub Type Information This DTC sets when the PCM grounds the relay circuit and more voltage than expected is detected on the relay circuit. This DTC also sets when the relay circuit is OFF and no voltage is detected on the relay circuit. The PCM expects to detect voltage coming through the relay coil to the relay circuit when it is not grounding it.
    PCM P0646:00 A/C Clutch Relay Control Circuit Low: No Sub Type Information This DTC sets when the relay circuit is OFF and ground is detected on the relay circuit.
    PCM P0647:00 A/C Clutch Relay Control Circuit High: No Sub Type Information This DTC sets when the PCM grounds the relay circuit and excessive current draw (short to voltage) is detected on the relay circuit while A/C is ON.

    Possible Sources 

    • Wiring, terminals or connectors
    • A/C clutch relay
    • PCM

    Visual Inspection and Pre-checks 

    • Inspect BJB fuses 22 (10A or 5A) and 10 (7.5A).
    • Inspect the A/C clutch relay for looseness or corrosion.

  2. 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.

  3. 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
      GFD328094Courtesy of FORD MOTOR COMPANY
      		 Ground
      A/C clutch relay socket 3
      GFD328094Courtesy of FORD MOTOR COMPANY
      		 Ground

    Are the voltages greater than 11 volts? 

    Yes  GO to  B2
    No  VERIFY BJB fuses 22 (10A or 5A) and 10 (7.5A) are OK. If not OK, REFER to OEM Electrical Wiring Diagram Introduction to identify the possible causes of the circuit short. If OK, REPAIR the circuit.

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

    Did the relay pass the component test? 

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

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

    • Ignition OFF.

    • Disconnect PCM 1.0L M/T C1233B, 1.0L A/T C1232B, 1.5L Duratec M/T C1551B, 1.5L Duratec A/T C1926B, 1.5L Duratorque C1381B or 2.0L Duratec C1915B.

    • Ignition ON.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      A/C clutch relay socket 2
      GFD328094Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is any voltage present? 

    Yes  REPAIR the circuit.
    No  GO to  B4

  6. 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
      GFD328095Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the resistance greater than 10, 000 ohms? 

    Yes  GO to  B5
    No  REPAIR the circuit.

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

    • Measure:

      1.0L M/T 

      Positive Lead Measurement / Action Negative Lead
      A/C clutch relay socket 2
      GFD328095Courtesy of FORD MOTOR COMPANY
      		 C1233B-2

      1.0L A/T 

      Positive Lead Measurement / Action Negative Lead
      A/C clutch relay socket 2
      GFD328095Courtesy of FORD MOTOR COMPANY
      		 Refer to C1232B-2

      1.5L Duratec M/T 

      Positive Lead Measurement / Action Negative Lead
      A/C clutch relay socket 2
      GFD328095Courtesy of FORD MOTOR COMPANY
      		 C1551B-40

      1.5L Duratec A/T 

      Positive Lead Measurement / Action Negative Lead
      A/C clutch relay socket 2
      GFD328095Courtesy of FORD MOTOR COMPANY
      		 C1926B-58

      1.5L Duratorque 

      Positive Lead Measurement / Action Negative Lead
      A/C clutch relay socket 2
      GFD328095Courtesy of FORD MOTOR COMPANY
      		 C1381B-13

      2.0L 

      Positive Lead Measurement / Action Negative Lead
      A/C clutch relay socket 2
      GFD328095Courtesy of FORD MOTOR COMPANY
      		 Refer to C1915B-2

    Is the resistance less than 3 ohms? 

    Yes  GO to  B6
    No  REPAIR the circuit.

  8. 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 TESTING
    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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