Seat Temperature Element: Description and Operation

Heated Seats Description and Operation

The front heated seat system consists of the following components.

* Left heated seat switch

* Right heated seat switch

* Heated seat control module

* Left seat cushion heater element

* Left seat back heater element

* Left seat temperature sensor

* Right seat cushion heater element

* Right seat back heater element

* Right seat temperature sensor

* HVAC control module

Power and Ground

Battery positive voltage is supplied at all times to the heated seat control module through a 20 A fuse located in the I/P fuse block. This voltage is used by the module to supply power to the seat heating elements. The module is grounded through the module ground circuit and G301.

Heated Seat Operation

The driver and passenger heated seats are controlled by a single heated seat control module that is located under the driver seat cushion. Both heated seats are controlled by separate heated seat switches that are located in the HVAC control module. When a heated seat switch is pressed, the HVAC control module sends a serial data message to the heated seat control module indicating the heated seat command. In response to this signal, the heated seat control module applies battery positive voltage through the heater element supply voltage circuit to the appropriate seat heating elements. The heated seat control module then sends a serial data message back to the HVAC control module to illuminate the appropriate temperature indicator.

Temperature Regulation

When the ignition is turned to the ON position, the heated seats will initialize in the OFF state. With each activation of the heated seat switch, the heated seat control module will cycle the temperature setting in the following manner: HIGH, LOW, and OFF.

The heated seat control module monitors the seat temperature through the temperature sensor signal circuit and the temperature sensor (thermistor) that is located in the seat cushion with the heater element. The temperature sensor is a variable resistor, it's resistance changes as the temperature of the seat changes. When the temperature sensor resistance indicates to the heated seat control module that the seat has reached the desired temperature, it will then cycle the element low reference control circuit open and closed in order to maintain the desired temperature.

Electrical Power Management

The load-shed operation is a means of reducing vehicle electrical loads during a low voltage or low battery state of charge (SOC) condition. During certain load-shed conditions, all heated seat functions will be disabled. Refer to Electrical Power Management Description and Operation Description and Operation.