Pinpoint Test T: The Heated Seats Are Inoperative - Rear

T1 CHECK THE VOLTAGE TO THE REAR HEATED SEAT MODULE
- Ignition OFF.
- WARNING: Turn the ignition OFF and wait one minute to deplete the backup power supply. Failure to follow this instruction may result in serious personal injury or death in the event of an accidental deployment.
  
  If equipped with inflatable safety belts, disconnect 2nd Row Safety Belt Inflator C3801 (LH). To access the electrical connector:
  - Remove 5 screws and the seat track inboard inner and outer covers.
  - Detach the cushion cover front and inboard retainers.
  - Lift the cushion cover and foam pad.
- Disconnect: Heated Seat Module C3304B.
- Ignition ON.
- Measure the voltage between:
  - heated seat module C3304B-2 , circuit CBP34 (VT/BN), harness side and ground.
  - heated seat module C3304B-1 , circuit SBB30 (BN/RD), harness side and ground.
    
    Fig 1: Measuring Voltage Between Heated Seat Module C3304B-1, Circuit SBB30 (BN/RD) And Ground
    Courtesy of FORD MOTOR CO.
Are the voltages greater than 11 volts?
- Yes : GO to T2 .
- No : VERIFY BJB fuse 30 (20A) and BCM fuse 34 (10A). If OK, REPAIR the affected circuit. If not OK, REFER to the OEM WIRING DIAGRAMS to identify the possible causes of the circuit short. TEST the system for normal operation.
  If equipped with inflatable safety belts, GO to T7.
T2 CHECK THE HEATED SEAT MODULE GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between heated seat module C3304B-5 , circuit GD374 (BK/WH), harness side and ground.
  
  Fig 2: Measuring Resistance Between Heated Seat Module C3304B-5, Circuit GD374 (BK/WH) And Ground
  Courtesy of FORD MOTOR CO.
Is the resistance less than 3 ohms?
- Yes : GO to T3 .
- No : REPAIR the circuit. TEST the system for normal operation.
  If equipped with inflatable safety belts, GO to T7.
T3 CHECK TEMPERATURE SENSOR CIRCUITS FOR A SHORT TO VOLTAGE
- Disconnect: Heated Seat Module C3304A.
- Ignition ON.
- Measure the voltage between:
  - heated seat module C3304A-3 , circuit VHS42 (GN), harness side and ground.
  - heated seat module C3304A-9 , circuit VHS45 (GY/BN), harness side and ground.
    
    Fig 3: Measuring Voltage Between Heated Seat Module C3304A-9, Circuit VHS45 (GY/BN) And Ground
    Courtesy of FORD MOTOR CO.
Is any voltage present?
- Yes : REPAIR the affected circuit. TEST the system for normal operation.
  If equipped with inflatable safety belts, GO to T7.
- No : GO to T4 .
T4 CHECK TEMPERATURE SENSOR CIRCUITS FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between:
  - heated seat module C3304A-3 , circuit VHS42 (GN), harness side and ground.
  - heated seat module C3304A-9 , circuit VHS45 (GY/BN), harness side and ground.
    
    Fig 4: Measuring Resistance Between Heated Seat Module C3304A-9, Circuit VHS45 (GY/BN) And Ground
    Courtesy of FORD MOTOR CO.
Are the resistances greater than 10, 000 ohms?
- Yes : GO to T5 .
- No : REPAIR the affected circuit. TEST the system for normal operation.
  If equipped with inflatable safety belts, GO to T7.
T5 CHECK THE TEMPERATURE SENSOR RETURN CIRCUIT FOR AN OPEN
- Measure the resistance between heated seat module C3304A-12 , circuit RHS41 (GN/BN), harness side and left rear heated seat C3304A-3 , circuit VHS42 (GN), harness side.
  
  Fig 5: Measuring Resistance Between Heated Seat Module C3304A-12, Circuit RHS41 (GN/BN) And Left Rear Heated Seat C3304A-3, Circuit VHS42 (GN)
  Courtesy of FORD MOTOR CO.
Is the resistance between 300 and 300, 000 ohms?
- Yes : GO to T6 .
- No : REPAIR circuit RHS41 (GN/BN). TEST the system for normal operation.
  If equipped with inflatable safety belts, GO to T7.
T6 CHECK THE AUXILIARY CLIMATE CONTROL ASSEMBLY OUTPUT
- Connect: Heated Seat Module C3304A.
- Connect: Heated Seat Module C3304B.
- Ignition ON.
- NOTE: The following measurement must be taken by back-probing the heated seat module C3304A.
  
  NOTE: The voltage on circuit CHS47 (VT/GN) should drop momentarily when the LH rear heated seat control button is pressed.
  
  Measure the voltage between heated seat module C3304A-2 , circuit CHS47 (VT/GN), harness side and ground by back-probing heated seat module C3304A-2 . Press the LH rear heated seat control button on the auxiliary climate control assembly and note the voltage.
  
  Fig 6: Measuring Voltage Between Heated Seat Module C3304A-2, Circuit CHS47 (VT/GN) And Ground
  Courtesy of FORD MOTOR CO.
Is the voltage greater than 11 volts before pressing the LH rear heated seat control button, then momentarily drops when the heated seat control button is pressed?
- Yes : INSTALL a new heated seat module. REFER to HEATED SEAT MODULE - REAR in this article. TEST the system for normal operation.
  If equipped with inflatable safety belts, GO to T7 .
- No : If the voltage is greater than 11 volts but did not drop when the LH rear heated seat button was pressed, INSTALL a new rear auxiliary climate control assembly. REFER to Auxiliary Climate Control Assembly .
  If the voltage is less than 11 volts, INSTALL a new heated seat module. REFER to HEATED SEAT MODULE - REAR in this article.
  
  TEST the system for normal operation.
  
  If equipped with inflatable safety belts, GO to T7 .
T7 CHECK FOR SRS DTCs
WARNING: Turn the ignition OFF and wait one minute to deplete the backup power supply. Failure to follow this instruction may result in serious personal injury or death in the event of an accidental deployment.
- Ignition OFF.
- Connect: 2nd Row Safety Belt Inflator C3801 (LH).
- Ignition ON.
- Using a scan tool, clear the RCM DTCs.
- Cycle the ignition OFF then ON.
- Using a scan tool, perform RCM self-test.
Are any RCM DTCs retrieved during self-test?
- Yes : REFER to SUPPLEMENTAL RESTRAINT SYSTEM for pinpoint test direction.
- No : The repair is complete. RETURN the vehicle to the customer.