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Pinpoint Test I : The Defrost System Is Inoperative - DATC (Dual Automatic Temperature Control)

  1. I1 CHECK FOR BCM (BODY CONTROL MODULE) DIAGNOSTIC TROUBLE CODES (DTCS)

    • Ignition ON.
    • Using a scan tool, perform BCM self-test.

    Are any BCM Diagnostic Trouble Codes (DTCs) present? 

    Yes  For DTC B1C84:12, GO to  I9For DTC B1C84:13 or B1C84:14, GO to  I4For all other Diagnostic Trouble Codes (DTCs), REFER to: Body Control Module (BCM)
    No  GO to  I2

  2. I2 CHECK THE REAR WINDOW DEFROST GRID VOLTAGE

    • Ignition OFF.
    • Disconnect: Isolator C4221 (4-door) or Rear Window Defrost Grid C402A (5-Door).
    • Start the engine.
    • Activate the rear window defrost switch.
    • For 4-door vehicles, measure:
      Positive Lead Measurement / Action Negative Lead
      C4221-1
      GFD60580Courtesy of FORD MOTOR COMPANY
      		 Ground
    • For 5-door vehicles, measure:
      Positive Lead Measurement / Action Negative Lead
      C402A-1 (5-door)
      GFD60580Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the voltage greater than 11 volts? 

    Yes  For 4-door vehicles, INSPECT the isolator and jumper harness to the rear window defrost grid for an open circuit. REPAIR as necessary. If the isolator and jumper harness are OK, GO to  I3For 5-door vehicles, GO to  I3
    No  GO to  I4

  3. I3 CHECK THE REAR WINDOW DEFROST GRID GROUND

    • Ignition OFF.
    • Disconnect: Rear Window Defrost Grid C402B .
    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C402B-1
      GFD60581Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the resistance less than 3 ohms? 

    Yes  CARRY OUT the Grid Wire Test. REFER to Component Test- Grid Wire Test . REPAIR the rear window defrost grid or INSTALL a new rear window glass. REFER to: Rear Window Glass - 4-Door  or REFER to: Rear Window Glass - 5-Door 
    No  REPAIR the circuit.

  4. I4 CHECK THE VOLTAGE TO THE REAR WINDOW DEFROST RELAY

    • Ignition OFF.
    • Disconnect: Rear Window Defrost Relay.
    • Ignition ON.
    • Measure:
      Positive Lead Measurement / Action Negative Lead
      GFD63983Courtesy of FORD MOTOR COMPANY

      Rear Window Defrost Relay, socket pin 1
      GFD60580Courtesy of FORD MOTOR COMPANY
      		 Ground
      GFD63983Courtesy of FORD MOTOR COMPANY

      Rear Window Defrost Relay, socket pin 3
      GFD60580Courtesy of FORD MOTOR COMPANY
      		 Ground

    Are the voltages greater than 11 volts? 

    Yes  GO to  I5
    No  VERIFY the BJB fuse 9 (30A) and 23 (5A) are OK. If OK, REPAIR the affected circuit. If not OK, REFER to OEM ELECTRICAL WIRING DIAGRAM INTRODUCTION (EXCEPT ELECTRIC VEHICLE) to identify the possible causes of the circuit short.

  5. I5 CHECK THE BCM (BODY CONTROL MODULE) OUTPUT

    NOTE: The following step uses a test light to simulate normal circuit loads. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.

    • Start the engine.
    • Activate the rear window defrost switch.
    • Measure:
      Positive Lead Measurement / Action Negative Lead
      GFD63983Courtesy of FORD MOTOR COMPANY

      Rear Window Defrost Relay, socket pin 1
      GFD60732Courtesy of FORD MOTOR COMPANY
      GFD63983Courtesy of FORD MOTOR COMPANY

      Rear Window Defrost Relay, socket pin 2

    Does the test light illuminate? 

    Yes  If DTC B1C84:13 or B1C84:14 is present, INSTALL a new rear window defrost relay. If DTC B1C84:13 or B1C84:14 is not present, GO to  I6
    No  GO to  I7

  6. I6 CHECK THE REAR WINDOW DEFROST RELAY

    • Ignition OFF.
    • Carry out the rear window defrost relay component test. REFER to COMPONENT TESTING for schematic and connector information.

    Did the rear window defrost relay pass the component test? 

    Yes  REPAIR circuit CRD06 (BN/YE) for an open.
    No  INSTALL a new rear window defrost relay.

  7. I7 CHECK THE REAR DEFROST SWITCH (CC_SW_DEFRST) PARAMETER IDENTIFICATION (PID)

    • Ignition ON.
    • Using a scan tool, view HVAC Module Parameter Identifications (PIDs).
    • Monitor the HVAC Module PID CC_SW_DEFRST while pressing and releasing the rear window defrost switch.

    Does the PID status change when the rear window defrost switch is pressed and released? 

    Yes  GO to  I8
    No  INSTALL a new HVAC module. REFER to: Heating, Ventilation and Air Conditioning (HVAC) Control Module

  8. I8 CHECK THE REAR WINDOW DEFROST RELAY CONTROL CIRCUIT FOR AN OPEN

    • Ignition OFF.
    • Measure:
      Positive Lead Measurement / Action Negative Lead
      GFD63983Courtesy of FORD MOTOR COMPANY

      Rear Window Defrost Relay, socket pin 2
      GFD60581Courtesy of FORD MOTOR COMPANY
      		 C2280B-22

    Is the resistance less than 3 ohms? 

    Yes  GO to  I10
    No  REPAIR the circuit.

  9. I9 CHECK THE REAR WINDOW DEFROST RELAY CONTROL CIRCUIT FOR A SHORT TO VOLTAGE

    • Ignition OFF.
    • Disconnect: Rear Window Defrost Relay.
    • Ignition ON.
    • Measure:
      Positive Lead Measurement / Action Negative Lead
      GFD63983Courtesy of FORD MOTOR COMPANY

      Rear Window Defrost Relay, socket pin 2
      GFD60580Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is any voltage present? 

    Yes  REPAIR the circuit.
    No  GO to  I10

  10. I10 CHECK FOR CORRECT BCM (BODY CONTROL MODULE) OPERATION

    • Ignition OFF.
    • Disconnect and inspect all the BCM connectors.
    • Repair:
      • corrosion (install new connector or terminals - clean module pins)
      • damaged or bent pins - install new terminals/pins as necessary
      • pushed-out pins - install new pins as necessary
    • Reconnect the BCM connectors and all previously disconnected rear window defrost system 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, INSTALL a new BCM.
    No  The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.
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