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Home >> Ford >> 2021 >> Expedition MAX SSV, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 578 (Rear Seats) >> Diagnosis And Testing >> Rear Seats >> Pinpoint Tests >> Pinpoint Test B : The Left Heated Rear Seat Is Inoperative >> Pinpoint Test B : The Left Heated Rear Seat Is Inoperative

Pinpoint Test B : The Left Heated Rear Seat Is Inoperative

WARNING: This page is about a different car, the 2020 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

  1. B1 CHECK THE HEATED SEAT SWITCH INPUT

    • Ignition OFF.

    • Disconnect Heated Rear Seat Module C3304A.

    • While pressing and releasing the left heated rear seat switch, measure:
      Positive Lead Measurement / Action Negative Lead
      C3304A-2
      GFD465490Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the resistance less than 3 ohms when the switch is pressed and greater than 10, 000 ohms when released? 

    Yes  GO to  B3
    No  GO to  B2

  2. B2 CHECK THE HEATED SEAT SWITCH CIRCUIT FOR AN OPEN OR SHORT TO GROUND

    • Disconnect Heated Rear Seat Switch C3182.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C3182-2
      GFD465490Courtesy of FORD MOTOR COMPANY
      		 C3304A-2
      C3182-2
      GFD465490Courtesy of FORD MOTOR COMPANY
      		 Ground

    Are the resistances less than 3 ohms between C3182-2 and C3304A-2, and greater than 10, 000 ohms between C3182-2 and ground? 

    Yes  INSTALL a new heated rear seat switch. REFER to: Heated Rear Seat Switch - SuperCrew .
    No  REPAIR the circuit.

  3. B3 CHECK FOR VOLTAGE TO THE HEATED SEAT MODULE

    • Disconnect Heated Rear Seat Module C3304B.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C3304B-1
      GFD465489Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the voltage greater than 11 volts? 

    Yes  GO to  B4
    No  REPAIR the circuit.

  4. B4 CHECK THE HEATER CIRCUITS AND HEATER MATS FOR AN OPEN

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C3304B-4
      GFD465490Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the resistance between 2.5 and 4.5 ohms? 

    Yes  GO to  B9
    No  GO to  B5

  5. B5 CHECK THE HEATER MAT GROUND CIRCUIT FOR AN OPEN

    • Disconnect Left Rear Backrest Heater Mat C3168.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C3168-2
      GFD465490Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the resistance less than 3 ohms? 

    Yes  GO to  B6
    No  REPAIR the circuit.

  6. B6 CHECK THE HEATER CIRCUIT FOR AN OPEN OR SHORT TO GROUND

    • Disconnect Left Rear Cushion Heater Mat C3167.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C3304B-4
      GFD465490Courtesy of FORD MOTOR COMPANY
      		 C3167-1

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C3304B-4
      GFD465490Courtesy of FORD MOTOR COMPANY
      		 Ground

    Are the resistances less than 3 ohms between C3304B-4 and C3167-1, and greater than 10, 000 ohms between C3304B-4 and ground? 

    Yes  GO to  B7
    No  REPAIR the circuit.

  7. B7 CHECK THE CUSHION HEATER MAT FOR AN OPEN

    • Measure the component side resistance  between:
      Positive Lead Measurement / Action Negative Lead
      GFD466677Courtesy of FORD MOTOR COMPANY

      C3167-1, Component Side
      GFD465490Courtesy of FORD MOTOR COMPANY
      GFD466677Courtesy of FORD MOTOR COMPANY

      C3167-4, Component Side

    Is the resistance between 1.5 and 2.5 ohms? 

    Yes  GO to  B8
    No  INSTALL a new cushion heater mat. REFER to: Seat Heater Mat Removal .

  8. B8 CHECK FOR AN OPEN OR A SHORT TO GROUND BETWEEN THE HEATER MATS

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C3167-4
      GFD465490Courtesy of FORD MOTOR COMPANY
      		 C3168-1

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C3167-4
      GFD465490Courtesy of FORD MOTOR COMPANY
      		 Ground

    Are the resistances less than 3 ohms between C3167-4 and C3168-1, and greater than 10, 000 ohms between C3167-4 and ground? 

    Yes  INSTALL a new backrest heater mat. REFER to: Seat Heater Mat Removal .
    No  REPAIR the circuit.

  9. B9 CHECK THE TEMPERATURE SENSOR CIRCUIT FOR A SHORT TO VOLTAGE

    • Ignition ON.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C3304A-3
      GFD465489Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is any voltage present? 

    Yes  REPAIR the circuit.
    No  GO to  B10

  10. B10 CHECK THE TEMPERATURE SENSOR CIRCUIT FOR A SHORT TO GROUND

    • Ignition OFF.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C3304A-3
      GFD465490Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the resistance greater than 10, 000 ohms? 

    Yes  GO to  B11
    No  REPAIR the circuit.

  11. B11 CHECK THE TEMPERATURE SENSOR AND CIRCUITS FOR AN OPEN

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C3304A-3
      GFD465490Courtesy of FORD MOTOR COMPANY
      		 C3304A-12

    Is the resistance between 300 and 300K ohms? 

    Yes  INSTALL a new heated rear seat module. REFER to: Heated Rear Seat Module - SuperCrew .
    No  GO to  B12

  12. B12 CHECK THE TEMPERATURE SENSOR FOR AN OPEN WITH THE HEATER MAT DISCONNECTED

    • Disconnect Left Rear Cushion Heater Mat C3167.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C3304A-3
      GFD465490Courtesy of FORD MOTOR COMPANY
      		 C3167-2
      C3304A-12
      GFD465490Courtesy of FORD MOTOR COMPANY
      		 C3167-3

    Are the resistances less than 3 ohms? 

    Yes  INSTALL a new cushion heater mat. REFER to: Seat Heater Mat Removal .
    No  REPAIR the circuit in question.
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