Pinpoint Test Y: The Heated Seat Is Inoperative - Left Rear Seat Does Heat But The Heated Seat Indicator Does Not Illuminate When Pressed

WARNING: This page is about a different car, the 2010 Lincoln MKX and 2010 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: Never install heated seat parts not intended for use on this vehicle. Parts released for other model years or vehicle lines are not compatible even if they appear visually and physically similar. Installing incorrect parts will result in heated seat system performance outside design specification. Failure to follow this instruction may result in serious personal injury.

Y1 CHECK CIRCUITS CHS49 (VT) AND CHS48 (YE) FOR A SHORT TO GROUND
- Disconnect: Left Rear Heated Seat Switch C722.
- Disconnect: Heated Seat Module C3162.
- Measure the resistance between:
  - heated seat module C3162-5, circuit CHS49 (VT), harness side and ground.
  - heated seat module C3162-4, circuit CHS48 (YE), harness side and ground.
    
    Fig 1: Measuring Resistance Between Heated Seat Module C3162-5, Circuit CHS49 (VT), Harness Side And Ground
    Courtesy of FORD MOTOR CO.
- Are the resistances greater than 10,000 ohms?
- Yes: GO to Y2 .
- No: REPAIR the affected circuit. TEST the system for normal operation.
Y2 CHECK CIRCUITS CHS49 (VT) AND CHS48 (YE) FOR AN OPEN
- Measure the resistance between:
  - left rear heated seat switch C722-3, circuit CHS49 (VT), harness side and heated seat module C3162-5, circuit CHS49 (VT), harness side.
  - left rear heated seat switch C722-4, circuit CHS48 (YE), harness side and heated seat module C3162-4, circuit CHS48 (YE), harness side.
    
    Fig 2: Measuring Resistance Between Left Rear Heated Seat Switch C722-3 And Heated Seat Module C3162-5
    Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
- Yes: GO to Y3 .
- No: REPAIR the affected circuit. TEST the system for normal operation.
Y3 CHECK THE HEATED SEAT HI INDICATOR
- Connect: Left Rear Heated Seat Switch C722.
- Ignition ON.
- Connect a fused jumper lead between heated seat module C3162- 4, circuit CHS48 (YE), harness side and C3162-1, circuit SBB07 (WH/RD), harness side.
  
  Fig 3: Connecting Fused Jumper Lead Between Heated Seat Module C329-4, Circuit CHS13 (VT/BN) And C329-1, Circuit SBB16 (VT/RD)
  Courtesy of FORD MOTOR CO.
- Does the hi indicator LED illuminate on the left rear heated seat switch?
- Yes: GO to Y4 .
- No: INSTALL a new rear heated seat switch. REFER to HEATED SEAT SWITCH - REAR SEAT . TEST the system for normal operation.
Y4 CHECK THE HEATED SEAT LOW INDICATOR
- Connect a fused jumper lead between heated seat module C3162- 5, circuit CHS49 (VT), harness side and C3162-1, circuit SBB07 (WH/RD), harness side.
  
  Fig 4: Connecting Fused Jumper Lead Between Heated Seat Module C329-5, Circuit CHS04 (YE/GY) And C329-1, Circuit SBB16 (VT/RD)
  Courtesy of FORD MOTOR CO.
- Does the low indicator LED illuminate on the left rear heated seat switch?
- Yes: INSTALL a new heated seat module. REFER to HEATED SEAT MODULE - REAR SEAT . TEST the system for normal operation.
- No: INSTALL a new rear heated seat switch. REFER to HEATED SEAT SWITCH - REAR SEAT . TEST the system for normal operation.