Heated seats – circuit operation

HEATED SEATS – CIRCUIT OPERATION

CIRCUIT OPERATION

Driver and passenger seat heaters are PTC regulated. Heated seat activation requests and timing functions are generated by the Hevac ECU while the Ignition Switch (X274) is in position II. The BeCM (Z238) provides power switching only for this function. In the case of both rear windows and the sunroof being operated at the same time or an uninitialised rear window or sunroof function being operated, the seat heaters will be inhibited to maintain current demand within a safe operating area. The signals are sent from the HEVAC ECU to the BeCM (Z238) and are active low. Therefore the lines are normally held at 12V.