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Home >> Ford >> 2005 >> Escape Hybrid, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1311 (HVAC - Climate Control System - General Information And Diagnostics - (Except Hybrid)) >> Diagnosis And Testing >> Climate Control System >> Pinpoint Tests >> Pinpoint Test B: DTC P0645 >> Pinpoint Test B: DTC P0645

Pinpoint Test B: DTC P0645

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.
  1. B1 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY 
    • Ignition OFF.
    • Disconnect: A/C Clutch Relay.
    • Ignition ON.
    • Measure the voltage between ground and the A/C clutch relay socket.
      Fig 1: Measuring Voltage Between Ground And A/C Clutch Relay Socket
      G06098541Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    • Yes:  CARRY OUT the A/C clutch relay component test.

      Refer to COMPONENT TESTING -- GASOLINE MODELS for component testing.

      If the relay tests OK, GO to B2  .

    • No:  INSTALL a new Battery Junction Box (BJB). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  2. B2 CHECK CIRCUIT CH302 (WH/BN) FOR A SHORT TO VOLTAGE 
    • Ignition OFF.
    • Disconnect: PCM C175B.
    • Ignition ON.
    • Measure the voltage between ground and PCM C175B-12, circuit CH302 (WH/BN), harness side.
      Fig 2: Measuring Voltage Between Ground And PCM C175B-12
      G06098542Courtesy of FORD MOTOR CO.
    • Is any voltage present? 
    • Yes:  REPAIR circuit CH302 (WH/BN) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
    • No:  GO to B3  .
  3. B3 CHECK CIRCUIT CH302 (WH/BN) FOR A SHORT TO GROUND 
    • Ignition OFF.
    • Measure the resistance between ground and PCM C175B-12, circuit CH302 (WH/BN), harness side.
      Fig 3: Measuring Resistance Between Ground And PCM C175B-12
      G06098543Courtesy of FORD MOTOR CO.
    • Is the resistance greater than 10,000 ohms? 
    • Yes:  GO to B4  .
    • No:  REPAIR circuit CH302 (WH/BN) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  4. B4 CHECK CIRCUIT CH302 (WH/BN) FOR AN OPEN 
    • Measure the resistance between A/C clutch relay socket, circuit CH302 (WH/BN) and PCM C175B-12, circuit CH302 (WH/BN), harness side.
      Fig 4: Measuring Resistance Between A/C Clutch Relay Socket, Circuit CH302 (WH/BN) And PCM C175B-12
      G06098544Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    • Yes:  GO to B5  .
    • No:  REPAIR circuit 321 (GY/WH) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
  5. B5 CHECK THE PCM CONNECTION 
    • Clear the DTCs.
    • Disconnect all the PCM connectors.
    • Check for:
      • corrosion.
      • pushed-out pins.
      • incorrectly seated connector.
    • Connect and correctly seat all the PCM connectors.
    • Operate the system.
    • Does the concern return? 
    • Yes:  INSTALL a new PCM. TEST the system for normal operation.
    • 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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