Pinpoint Test N: The Heated Seats Are Inoperative - Rear

N1 CHECK THE VOLTAGE TO THE REAR HEATED SEAT MODULE
- Disconnect: Heated Seat Module C3304b.
- Ignition ON.
- Measure the voltage between:
  - heated seat module C3304b-2, circuit CBP35 (YE/GY), harness side and ground.
  - heated seat module C3304b-1, circuit SBP18 (YE/RD), harness side and ground.
    
    Fig 1: Measuring Voltage Between Heated Seat Module C3304b-1, Circuit SBP18 (YE/RD), Harness Side And Ground
    Courtesy of FORD MOTOR CO.
- Are the voltages greater than 10 volts?
- Yes : GO to N2.
- No : VERIFY Smart Junction Box (SJB) fuses 18 (20A) and 35 (10A) are OK. If OK, REPAIR the affected circuit. TEST the system for normal operation. If not OK, REFER to the SYSTEM WIRING DIAGRAMS article to identify the possible causes of the circuit short.
N2 CHECK THE REAR HEATED SEAT MODULE GROUND CIRCUITS FOR AN OPEN
- Ignition OFF.
- Disconnect: Backrest Heater Mat C3168.
- Measure the resistance between left rear seat backrest heater mat C3168-1, circuit GD145 (BK/BU), harness side and ground.
  
  Fig 2: Measuring Resistance Between Left Rear Seat Backrest Heater Mat C3168-1, Circuit GD145 (BK/BU), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Measure the resistance between heated seat module C3304b-5, circuit GD145 (BK/BU), harness side and ground.
  
  Fig 3: Measuring Resistance Between Heated Seat Module C3304b-5, Circuit GD145 (BK/BU), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
- Yes : GO to N3.
- No : REPAIR the affected circuit. TEST the system for normal operation.
N3 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 4: Measuring Voltage Between Heated Seat Module C3304a-9, Circuit VHS45 (GY/BN), Harness Side And Ground
    Courtesy of FORD MOTOR CO.
- Is voltage present on either circuit?
- Yes : REPAIR the affected circuit. TEST the system for normal operation.
- No : GO to N4.
N4 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 5: Measuring Resistance Between Heated Seat Module C3304a-9, Circuit VHS45 (GY/BN), Harness Side And Ground
    Courtesy of FORD MOTOR CO.
- Are the resistances greater than 10, 000 ohms?
- Yes : GO to N5.
- No : REPAIR the affected circuit. TEST the system for normal operation.
N5 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 6: 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 : INSTALL a new heated seat module. REFER to HEATED SEAT MODULE - REAR . TEST the system for normal operation.
- No : REPAIR circuit RHS41 (GN/BN). TEST the system for normal operation.