Pinpoint Test F: The Heated Seats Are Inoperative
Seats
Pinpoint Test F: The Heated Seats are Inoperative
Normal Operation
With the ignition ON, voltage is supplied from the Smart Junction Box (SJB) to each heated seat relay coil on circuit CBP43 (GY). Battery voltage is also supplied to the heated seat relay contacts (hot at all times) on circuit SBB16 (VT/RD). When the heated seat buttons are pressed, the Front Controls Interface Module (FCIM) illuminates the heated seat indicators and transmits a system request message to the HVAC module on the communication network. The HVAC module provides ground to heated seat relay coil circuits CHS30 (GN/YE) (driver) and CHS29 (WH/BU) (passenger) to operate the system. The engine must be running and both modules must be communicating correctly for the system to operate.
The HVAC module monitors the heated seat relay coil circuits for open, short to ground and short to voltage. If circuit faults are detected and DTCs are set for both seats, the HVAC module removes ground from the relay coils to disable the system (refer to HVAC Module DTC Chart Seats). The HVAC module also transmits network communication messages to the FCIM (Front Controls Interface Module) to deactivate the heated seat indicators. PIDs are available in the FCIM (Front Controls Interface Module) using a scan tool to check the heated seat switches and confirm correct module communication.
The heated seat system does not time-out and remains on until switched off or the engine is off.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- FCIM (Front Controls Interface Module)
- HVAC module
PINPOINT TEST F : THE HEATED SEATS ARE INOPERATIVE
F1 CHECK THE HEATED SEAT INDICATORS
- Start the engine.
- Operate both heated seats on and off.
Do all the heated seat indicators operate correctly?
Yes
GO to F4.
No
GO to F2.
F2 CHECK SCAN TOOL COMMUNICATION WITH THE FCIM (Front Controls Interface Module) AND MONITOR THE PIDs
- Enter the following diagnostic mode on the scan tool: DataLogger- FCIM (Front Controls Interface Module)- PIDs.
- Driver Heated Seat (CC_SW_D_HSEATS)
- Passenger Heated Seat (CC_SW_P_HSEATS)
- Monitor the FCIM (Front Controls Interface Module) PIDs while pressing the heated seat switches.
Do the PID values agree with the switch positions?
Yes
GO to F3.
No
If the FCIM (Front Controls Interface Module) does not communicate with the scan tool, REFER to Information Bus to diagnose the module communication error. Otherwise, INSTALL a new FCIM (Front Controls Interface Module). TEST the system for normal operation.
F3 RETRIEVE FCIM (Front Controls Interface Module) DTCs
- Enter the following diagnostic mode on the scan tool: Self Test- FCIM (Front Controls Interface Module).
Are any FCIM (Front Controls Interface Module) DTCs retrieved?
Yes
For all FCIM (Front Controls Interface Module) DTCs, REFER to the Master DTC Chart in Body Control Systems Body Control Systems.
No
GO to F4.
F4 CHECK SCAN TOOL COMMUNICATION WITH THE HVAC MODULE AND RETRIEVE DTCs
- Enter the following diagnostic mode on the scan tool: Self Test- HVAC module.
Are any HVAC module DTCs retrieved?
Yes
REFER to HVAC Module DTC Chart Seats.
No
If the HVAC module does not communicate with the scan tool, REFER to Information Bus to diagnose the module communication error. Otherwise, GO to F5.
F5 CHECK FOR VOLTAGE TO THE HEATED SEAT RELAY BOX
- Disconnect: Driver Heated Seat Relay.
- Ignition ON.
- Measure the voltage between:
- heated seat relay box pin 3, circuit SBB16 (VT/RD) and ground.
- heated seat relay box pin 1, circuit CBP43 (GY) and ground.
Are the voltages greater than 10 volts?
Yes
INSTALL a new HVAC module. REPEAT the self-test. CLEAR the DTCs. TEST the system for normal operation.
No
VERIFY Battery Junction Box (BJB) fuse 16 (20A) and SJB (Smart Junction Box) fuse 43 (10A) are OK. If OK, REPAIR the circuit(s). If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short [1][2]Diagrams By Number. TEST the system for normal operation.