Pinpoint Test A: Both Heated Rear Seats Are Inoperative
- Refer to CLIMATE CONTROLLED SEATS
for schematic and connector information.
Normal Operation and Fault Conditions
The rear heated seat module receives power through the normally closed contacts of the snowplow relay (integral to the BJB). When the LH or RH heated rear seat control switch is activated with the ignition ON, a momentary ground signal is supplied to the heated seat module to operate the system. The system cycles through high heat mode, low heat mode or OFF, each time the switch is pressed. The heated seat module supplies voltage to the LH or RH rear seat cushion and backrest heater mats, which are connected in series. Seat temperature is maintained by the heated seat module using a sensor contained within each cushion heater mat. The heated seat module supplies a reference voltage to the temperature sensor and monitors the return signal from the temperature sensor for controlling current flow to the heater mats. The heated seat module remains ON, heating the seat and maintaining temperature until switched OFF or the ignition voltage is switched OFF.
REFER to: Rear Seats - System Operation and Component Description .
Possible Sources
- Fuse(s)
- Wiring, terminals or connectors
- Heated rear seat switch
- Heated rear seat module
- BJB
Visual Inspection and Pre-checks
- If equipped with the snowplow feature, verify that snowplow mode is not active. For information about snowplow mode, refer to the Owner's Literature.
- Verify BCM fuse 36 (15A) and BJB fuse 19 (20A) are OK.
- A1 CHECK FOR VOLTAGE TO THE HEATED REAR SEAT MODULE
- Ignition OFF.
- Disconnect Heated Rear Seat Module C3304B.
- Ignition ON.
- Measure:
Positive Lead Measurement / Action Negative Lead C3304B-1 Ground
Is the voltage greater than 11 volts?
Yes GO to A2 No VERIFY BJB fuse 19 (20A) is OK. If OK, GO to A7 If not OK, REFER to the OEM WIRING DIAGRAMS to identify the possible causes of the circuit short. - A2 CHECK FOR IGNITION VOLTAGE TO THE HEATED REAR SEAT MODULE
- Measure:
Positive Lead Measurement / Action Negative Lead C3304B-2 Ground
Is the voltage greater than 11 volts?
Yes GO to A3 No VERIFY BCM fuse 36 (15A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the OEM WIRING DIAGRAMS to identify the possible causes of the circuit short. - Measure:
- A3 CHECK THE HEATED REAR SEAT MODULE GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure:
Positive Lead Measurement / Action Negative Lead C3304B-5 Ground
Is the resistance less than 3 ohms?
Yes GO to A4 No REPAIR the circuit. - A4 VERIFY THE HEATED REAR SEAT SWITCH IS PROVIDING A GROUND INPUT SIGNAL TO THE HEATED SEAT MODULE
- 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 Ground
Is the resistance less than 3 ohms when the switch is pressed and greater than 10, 000 ohms when released?
Yes GO to A6 No GO to A5 - A5 CHECK THE HEATED REAR SEAT SWITCH GROUND CIRCUIT FOR AN OPEN
- Disconnect Heated Rear Seat Switch C3182.
- Measure:
Positive Lead Measurement / Action Negative Lead C3182-8 Ground
Is the resistance less than 3 ohms?
Yes INSTALL a new heated rear seat switch. REFER to: Heated Rear Seat Switch - SuperCrew . No REPAIR the circuit. - A6 CHECK THE TEMPERATURE SENSOR RETURN CIRCUIT FOR AN OPEN
Is the resistance between 300 and 300K ohms?
Yes INSTALL a new heated rear seat module. REFER to: Heated Rear Seat Module - SuperCrew . No REPAIR the circuit. - A7 CHECK THE BCM (BODY CONTROL MODULE) DIAGNOSTIC TROUBLE CODES (DTCS)
- Using a diagnostic scan tool, perform the BCMBCM self-test.
Was DTC B14B6:12 or B14B6:14 retrieved?
Yes REFER to: Snow Plow Package . No GO to A8 - A8 CHECK THE HEATED REAR SEAT MODULE VOLTAGE FEED CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: BJB C1035B.
Is the resistance less than 3 ohms?
Yes INSPECT C1035D for corrosion or damaged and/or pushed-out pins. REPAIR as necessary. If OK, INSTALL a new BJB. No REPAIR the circuit.