Pilot V6-3.5L (2004)
Seat Heater: Description and Operation
How the Circuit Works
With the ignition switch in ON (II), battery voltage is provided through fuse 3 (in the driver's under-dash fuse/relay box) to the coil of the seat heater
relay which is grounded at G201. 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 (driver's only).
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 G601. 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 seat cushion and seat back heaters. The seat 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 G601. Since the seat 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 113 °F (45 °C) and opens above 140 °F (60 °C), while the
thermostat is closed below 110 °F (43 °C) and opens above 117 °F (53 °C). This helps maintain a constant seat temperature and prevent overheating.
The front passenger's seat cushion heaters work the same way.