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Home >> Ford >> 2021 >> Expedition Platinum, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 74 (Glass, Frames And Mechanisms) >> Diagnosis And Testing >> Glass, Frames and Mechanisms >> Pinpoint Test(s) >> Pinpoint Test A : The Defrost System Is Inoperative >> Pinpoint Test A : The Defrost System Is Inoperative

Pinpoint Test A : The Defrost System Is Inoperative

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  1. A1 CHECK THE REAR WINDOW DEFROST GRID VOLTAGE

    • Ignition OFF.

    • Disconnect: Heated Rear Window Element (RH) C3368B .

    • Start the engine.

    • Activate the rear window defrost switch.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C3368B-1
      GFD200491Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the voltage greater than 11 volts? 

    Yes  GO to  A2
    No  VERIFY BJB fuse 12 (40A) is OK. If not OK, REFER to the OEM Wiring Diagrams to identify the possible causes of the circuit short. If OK, GO to  A3

  2. A2 CHECK THE REAR WINDOW DEFROST GRID GROUND

    • Ignition OFF.

    • Disconnect: Heated Rear Window Element (LH) C3368A .

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C3368A-1
      GFD200490Courtesy 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, INSTALL a new rear window glass sliding panel or INSTALL a new rear window glass assembly as necessary. Refer to: Rear Window Glass Sliding Panel . Refer to: Fixed Glass .
    No  REPAIR the circuit.

  3. A3 CHECK THE REAR WINDOW DEFROST RELAY CONTROL CIRCUIT FOR VOLTAGE

    • Ignition OFF.

    • Disconnect: Rear Window Defrost Relay.

    • Ignition ON.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      GFD206685Courtesy of FORD MOTOR COMPANY

      Rear Window Defrost Relay, socket pin 1
      GFD200491Courtesy of FORD MOTOR COMPANY
      		 Ground
      GFD206685Courtesy of FORD MOTOR COMPANY

      Rear Window Defrost Relay, socket pin 3
      GFD200491Courtesy of FORD MOTOR COMPANY
      		 Ground

    Are the voltages greater than 11 volts? 

    Yes  GO to  A4
    No  REPAIR the circuit or INSTALL a new BJB as necessary.

  4. A4 CHECK THE FCIM (FRONT CONTROLS INTERFACE MODULE) OUTPUT

    NOTE: The following step uses a test lamp to simulate normal circuit loads. Use only a Rotunda Test Lamp (SGT27000) or 250- 300mA incandescent bulb test lamp. To avoid connector terminal damage, use the Rotunda Flex Probe kit for the test lamp probe connection to the vehicle. Do not use the test lamp probe directly on any connector.

    • Connect:
      Positive Lead Measurement / Action Negative Lead
      GFD206685Courtesy of FORD MOTOR COMPANY

      Rear Window Defrost Relay, socket pin 1
      GFD205851Courtesy of FORD MOTOR COMPANY
      GFD206685Courtesy of FORD MOTOR COMPANY

      Rear Window Defrost Relay, socket pin 2

    • Start the engine.

    • Activate the rear window defrost switch.

    Does the test light illuminate? 

    Yes  GO to  A5
    No  GO to  A6

  5. A5 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 the open in the rear window defrost relay output circuit.
    No  INSTALL a new rear window defrost relay.

  6. A6 CHECK THE REAR WINDOW DEFROST RELAY CONTROL CIRCUIT FOR A SHORT TO VOLTAGE

    • Ignition OFF.

    • Ignition ON.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      GFD206685Courtesy of FORD MOTOR COMPANY

      Rear Window Defrost Relay, socket pin 2
      GFD200491Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is any voltage present? 

    Yes  REPAIR the circuit.
    No  GO to  A7

  7. A7 CHECK THE REAR WINDOW DEFROST RELAY CONTROL CIRCUIT FOR AN OPEN

    • Ignition OFF.

    • If equipped with multi-function display, measure:
      Positive Lead Measurement / Action Negative Lead
      GFD206685Courtesy of FORD MOTOR COMPANY

      Rear Window Defrost Relay, socket pin 2
      GFD200490Courtesy of FORD MOTOR COMPANY
      		 C2402A-7

    • If not equipped with multi-function display, measure:
      Positive Lead Measurement / Action Negative Lead
      GFD206685Courtesy of FORD MOTOR COMPANY

      Rear Window Defrost Relay, socket pin 2
      GFD200490Courtesy of FORD MOTOR COMPANY
      		 C2402A-4

    Is the resistance less than 3 ohms? 

    Yes  GO to  A8
    No  REPAIR the circuit.

  8. A8 CHECK FOR CORRECT FCIM (FRONT CONTROLS INTERFACE MODULE) OPERATION

    • Ignition OFF.

    • Disconnect and inspect all the FCIM 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 FCIM 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, Refer to FCIM Hardware Testing.
    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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