Description And Operation: Operation

Heated Systems Modules: 

• The CSWM controls the heated seat system.
• The SCCM is the interface between the heated steering wheel and the vehicle.
• The Steering Wheel Switch (SWS) converts hard wired sense and return information into a LIN bus message and sends to the SCCM.
• The BCM gates messages between the CAN C bus and the CAN IHS. Additionally the BCM provides vehicle information to the CSWM.

Refer to HEATED STEERING WHEEL - DESCRIPTION AND OPERATION for heated steering wheel information.

Heated Seats: 

• The heated seat system operates on battery current received through fused ignition switch output (RUN) circuits and will only operate when the engine is running.
• The CSWM directly provides power to the seat heating elements in the seat cushions and seat backs for seat heating.
• The driver seat heat system and passenger seat heat system each consist of a cushion element connected in parallel with a back element.
• A thermistor sensor feedback from each seat heating element to the CSWM is used to regulate the heater outputs to prevent any seats temperature from rising above the set points. If a seat temperature exceeds the set point the CSWM automatically disables the system.
  • The high level cutoff value range is from 50-60°C (120-140°F) in increments of 1 degrees Fahrenheit. The typical value is 54°C (129°F).
  • The low level cutoff value range is from 50-60°C (120-140°F) in increments of 1 degrees Fahrenheit. The typical value is 55°C (131°F).
• The CSWM will also turn off the heated seat elements if an open or short in the heating element circuit is detected.
• Each time a heated seat request signal is received by the CSWM, the heated seat output will cycle from Off to High, High to Low and Low to Off. (i.e. the first press cycles from Off to High, the next press cycles from High to Low and the next press cycles from Low to Off.)
• When the CSWM receives the actuation request, the CSWM activates the heating element output at the high level and transmits a message on the CAN IHS bus to indicate the current output state is high.
• The CSWM automatically transitions the output from high to low after a maximum period of 60 minutes has elapsed and transmits a message on the CAN IHS bus to indicate the current output state is low.
• The CSWM automatically transitions the output from low to off after a maximum period of 45 minutes has elapsed and transmits a message on the CAN IHS bus to indicate the current output state is off.

When pressing the heated seat switch:

• A CAN IHS bus message request is generated.
• The CSWM receives the "Heated Seat request" from the CAN IHS bus.
• The CSWM broadcasts a confirmation of actuation message over the CAN IHS bus.
• The CSWM energizes an integral solid-state relay, which supplies Pulse Width Modulated (PWM) current to the heating elements of the designated seat(s).
• The CSWM monitors the seat temperature.

The CSWM is diagnosed using a scan tool and will automatically turn off the heating elements if it detects an open or low short in a heating element circuit.