Heated seats – circuit operation rev: 11/2000

HEATED SEATS – CIRCUIT OPERATION REV: 11/2000

CIRCUIT OPERATION

Driver and passenger seat heaters are temperature regulated by a thermal switch located in each seat. The seat heaters will only operate while the engine is running and, once selected, remain energised until selected off or until the ignition is turned off. Seat heater activation is initiated by pressing the appropriate switch on the HEVAC ECU. Provided the engine is running, the HEVAC ECU transfers the request to the BeCM by switching the applicable output from Vbatt to ground for the duration that the switch is pressed. On receipt of the seat heater request, the BeCM switches the appropriate seat heater output from ground to Vbatt. To prevent current overload, the BeCM inhibits the seat heater output if both rear windows and the sunroof are operated together, or if an uninitialised rear window or sunroof are operated. The seat heater power output from the BeCM passes through the thermal switch and the heating elements, in the seat cushion and seat squab, to ground. The temperature of the heating elements is regulated by the opening and closing of the thermal switch.