GM Service Manual Online
For 1990-2009 cars only

Heated Seat System Components

The heated seats system consists of the following components:

    • The heated seat switch
    • The driver heated seat relay module
    • The passenger heated seat relay module
    • The driver heated seat thermistor
    • The passenger heated seat thermistor
    • The driver back cushion heater element
    • The driver seat cushion heater element
    • The passenger back cushion heater element
    • The passenger seat cushion heater element
    • The HVAC/DIC/DRL/HEATED SEAT 10A fuse
    • The PWR/HEATED SEAT PSD 30A circuit breaker

Heated Seat System Controls

The heated seats are controlled by the following components:

    • Headed seat switches
    • Heated seat relay modules

Heated Seat Operation

The driver and front passenger seats are heated using electric heater elements with approximately 1 ohm of resistance each and are located in the lower seat cushions and seat backs. Voltage to the heater elements is controlled by the heated seat relay modules using inputs from the heated seat switches and the heated seat thermistors. The heated seat relay modules and thermistors are part of the lower seat cushion heater element assemblies. Ignition voltage is supplied to the heated seat switch assembly and is used to supply a signal voltage to the relay module and to illuminate the heated seat indicator during heated seat operation. Battery voltage is supplied to the relay module through a PTC device located in the seat harness which provides extra circuit protection. During heated seat operation the relay module switches the battery voltage supply circuit to the heater element supply circuit. The seat cushion and back heater elements are wired in series and always operate simultaneously. The seat temperature is regulated by the relay module using an input from the thermistor located in the seat cushion. The thermistor is a temperature sensitive variable resistor and the relay module determines the seat cushion temperature by monitoring the signal voltage supplied to the thermistor. When the desired seat temperature has been reached the relay module will open and close the supply voltage to the heater elements as necessary in order to maintain the seat temperature.