Heated Seats

The heated seat system is designed to warm the seat cushion and backrest to approximately 37° C (98.6° F) when in the LOW position and 44° C (111.2° F) when in the HIGH position. The system will only operate when the ignition switch is in RUN. Components in the system are the LH and RH heated seat switches, LH and RH heated seat relay module and the heating elements in the seat cushion and seat back.

When the ignition switch is in RUN and the LH or RH heated seat switch is placed in the LOW or HIGH position, battery voltage from the Trunk Compartment Fuse Block CONSOLE Fuse is applied through the switch contacts to the LH or RH heated seat relay module at terminal C and terminal B.

When battery voltage is applied to the respective heated seat relay module at terminal C, the relay contacts close to apply battery voltage from the Trunk Compartment Fuse Block HTD SEAT L Fuse or HTD SEAT R Fuse to the heating elements in the seat cushions. The heating elements in the seat cushion and backrest are wired in a series circuit and are grounded through CKT 850 (BLK) to ground G302.

Temperature Regulation
The position of the heated seat switch determines the regulated temperature of the seats. If the switch is in the LOW position, a 200 ohm resistor is in series with the heated seat relay module's LOW/HIGH input at terminal B. When the switch is in the HIGH position, a 310 ohm resistor is in series with the LOW/HIGH input terminal B.

The heated seat relay module differentiates the switch positions by monitoring the voltage drop across the switch.

To regulate the temperature of the seats, a temperature sensor is installed in the seat cushion. The sensor is a variable resistor (its resistance changes as the temperature of the seat cushion changes). The heated seat relay module monitors the sensor resistance through CKT 952 (YEL/BLK) at the sensor input terminal E. When the heated seat switch is in the LOW position and the heating element temperature reaches 37° C (98.6° F), the module opens its contacts removing battery voltage from the heating elements.

If the heated seat switch is in the HIGH position, battery voltage is removed when the heating elements temperature reaches 44° C (111.2° F). The heated seat relay module will cycle on and off to maintain the desired temperature. The system will remain active until the system or the ignition switch is turned off.

ON Indicator
When the heated seat switch is in either the LOW or HIGH position, battery voltage is applied through the closed switch contacts to the ON indicator LED to illuminate the indicator. The indicator is grounded through CKT 850 (BLK) at ground G302.