Module, Heated Seat (HSM): Description
The Heated Seat Module (HSM) (1) is located under the passenger front seat. It has a multiple electrical connectors (3) and a push pin style retainer (4) that secures the module to the seat pan once the module latches (2, 5) are engaged. The module can be accessed from under the passenger seat with the seat in the full back and up position.
The HSM is a Controller Area Network-Interior High Speed (CAN-IHS) bus controller providing outputs to the power seats, heated seat pads, heated steering wheel, and ventilation for up to two seats. The HSM receives commands over the CAN-IHS bus from the Body Control Module (BCM). The seat thermistor is hardwired to the HSM.
Heated Seats - The HSM uses a Pulse Width Modulation (PWM) to provide power to the seat cushion and back heating elements. The temperature sensor thermistor is located in the seat cushion. The thermistor sensor feedbacks from each seat heating element to the HSM to regulate the heater outputs to prevent any seat temperature to rise above set points. Seat heating has two selectable heat settings which are HI and LO. Depending on thermistor reading, the HSM will start the heater output by adjusting the PWM heat level according to internal controller calibrations.
Vented Seats - The seat venting has two selectable speeds for the fans. For seat venting, each press of the switch button will cause the seat to change venting modes. The HSM has a single low side control signal to control each vented seat. The HSM does not directly drive the vent motors.
Heated Steering Wheel - The HSM provides power to the steering wheel heating element. The heated steering wheel is standard when the vehicle is equipped with front heated seats. During normal operation, the HSM will switch on the power for the heated wheel only if the engine is running. The heated steering wheel temperature sensor is hardwired to the Electronic Vehicle Information Center (EVIC) switch which sends that information over a Local Interface Network (LIN) through the Steering Column Control Module (SCCM) to the BCM. The thermistor sensor feedbacks from the steering wheel heating element via the CAN-IHS bus to the HSM regulating the heater output to prevent the wheel temperature to rise above a controller calibrated maximum threshold temperature set point.