Seats: Description and Operation

The heated seat system is made up of the seat heater main relay, left and right seat heater relays, and left and right seat heaters. The seat heater switch contains an indicator light. Each seat heater relay contains two sets of coils and contacts. Each seat heater contains a seat cushion and seat back. The seat cushion contains two thermal switches and a heater element. The seat back contains a thermal switch and a heater element.

When the ignition switch is in ON (II) the seat heater main relay receives battery voltage through fuse 11. Voltage through fuse 6 is supplied to the left and right seat heater switches. The left and right seat heaters are identical.

When you push the seat heater switch to ON, its internal "on indicator" receives battery power causing the indicator to come ON. At the same time, battery voltage from the seat heater switch is supplied to the seat heater relay coil via the GRN/WHT wire. The two relay coils energize because they are grounded through the seat cushion internal thermal switch. One energized coil grounds the seat back heater element, the other one supplies battery voltage to the seat cushion via the WHT/RED wire. This same voltage is supplied to the seat back heater, causing it to heat up. The seat cushion then heats up because it's tied directly to ground G521.

If the seat back reaches 158°F (7O°C), its internal thermal switch opens, removing voltage from the GRN wire to the seat back heater element until the seat cools down and the switch closes. When the thermal switch reaches 122°F (5O°C) it opens again removing voltage to the seat cushion heater element and seat back heater element until the seat cools down and the thermal switch closes. When the thermal switch reaches 1O4°F (4O°C) it opens, removing ground from the seat heater relay coil. The relay is then deactivated, removing power and ground from the entire seat heater until the thermal switch cools and closes.