Heated Seat Block Diagram

Fig 1: Heated Seat Block Diagram

Courtesy of GENERAL MOTORS COMPANY

The driver and front passenger heated seats are controlled by separate heated seat switches that are located in the radio/HVAC controls. When a heated seat switch is pressed, a serial message is sent from the radio/HVAC controls to the seat heating control module indicating the heated seat command. In response to this message, the seat heating control module applies a high side drive pulse width modulated (PWM) signals driven at the required duty cycles to generate the appropriate effective voltage to the heating elements to attain the commanded seat temperature. The seat heating control module then sends a serial data message back to the radio/HVAC control to either illuminate or turn off the appropriate temperature indicator.

This heated seat system utilizes a self-regulating heating element system, which is different from the non-regulated heating element systems with seat temperature sensors previously used on GM vehicles. In the self-regulating type of system, temperature feedback to a control module is not required for temperature regulation. The heating element material itself regulates the surface temperature based on the effective voltage applied to the heating element.