For 1990-2009 cars

### Heated Seats System Operation

The driver and front passenger seats are heated using electric heater elements located in the seat cushions and seat backs. The heated seat control module is part of the seat cushion element and harness assembly, and controls the battery positive voltage used to supply the seat heater elements. The heated seat switch and a thermistor located in the seat cushion are connected in series and provide a single input to the heated seat control module. Ignition voltage is supplied to the heated seat switch from the HVAC 20A fuse in the underhood BEC. When the heated seat switch is in the high or low positions voltage is supplied through one of the internal resistors to the switch signal circuit. The heated seat switch signal circuit is grounded through the seat cushion thermistor which is a temperature sensitive variable resistor. The heated seat switch signal circuit input to the heated seat control module is spliced from the circuit between the switch and the thermistor, where the voltage level is determined by the resistance of both components. Once the seat cushion has reached the desired temperature the heated seat control module will maintain the heated seat switch signal circuit voltage level of 6 to 7.5 volts by switching the heater element supply circuit on or off as necessary. The passenger heated seat switch must be enabled through the seat belt switch in order for heated seat operation to occur.