3.2TL TYPE S V6-3.2L SOHC (2002)
Seat Heater: Description and Operation
Seat Heaters
How the Circuit Works
With the ignition switch in ON (II), battery voltage is provided through fuse 4 (in the driver's under-dash fuse/relay box) to the coil of the seat heater
relay which is grounded at G302. The coil of the relay is then energized, which closes the relay contacts providing voltage through fuse 3 (in the
passenger's under-dash fuse/relay box) and the relay to both seat heater switches.
Two heaters are provided in each front seat. One is located in the seat cushion and the other is in the seat back.
When the driver's seat heater switch is in the LOW position, current flows in series through the seat heater switch, the WHT/BLU wire, and the seat
cushion and seat back heaters to G551. Current is limited because it is flowing through both seat heaters in series, making the seat warm enough for
moderately cold weather.
When the switch is in the HIGH position, current flows in parallel through the seat heater switch, the WHT/RED wire, the circuit breaker and thermostat,
and through the cushion and seat back heaters ( 99 front passenger's). The cushion heater is grounded through the WHT/BLU wire and the driver's seat
heater switch to G501. The seat back heater is grounded at G551. Since the cushion and seat back heaters are now in parallel, current flow through them
increases and the seat warms to its maximum temperature. The circuit breaker is closed below 86 degrees F (30 degrees C) and opens above 122
degrees F (50 degrees C), while the thermostat is closed below 93 degrees F (34 degrees C) and opens above 109 degrees F (43 degrees C). This
helps maintain a constant seat temperature and prevent overheating. The front passenger's seat heaters work the same way.
