Optional Seat Heating

Optional Seat Heating

The optionally equipped E46 Seat Heating feature is similar to previous Systems with two preset temperature settings. The seat heating system consists of the following components:
- Console mounted, temperature regulating seat heater switches.
- Two section (Seat base and back) carbon fiber heating pad with temperature sensor. If seat heating is equipped on the sport seat, a third heating pad is incorporated into the thigh support.

Seat Heating Switch







Each seat push-button switch contains two LED's that correspond with the two preset temperature settings.

- Both LED's ON, Higher temperature setting selected
- Left LED ON only, Lower temperature setting selected

The switches contain temperature regulation electronics that provide 100% current flow to the seat heating element pad when first activated providing fast heat build up. Once the temperature is attained, the electronics regulates the current flow to stabilize the set temperature.

The switches provide operating current to the seat heaters until switched off. There is no preset time limit of operation.

If the battery voltage drops below 11.4 volts, the seat heating switch cuts the power supply to the heating pads but the LED's in the switch remain illuminated. The seat heating switches restore power to the heating pads when the battery voltage raises above 12.2 volts for more than five seconds.

Carbon Fiber Heating Pads

In each seat is a two section (three section on sport seats), heating pad. The sections are wired in parallel . The heating pads are resistors which when provided operating power from the seat heating switches produce radiant heat to the following temperatures.

- High temperature setting selected (40 °C at heating pad)
- Lower temperature setting selected (37 °C at heating pad)

The seat base heating element also contains a temperature sensor for feedback to the seat switch to provide the temperature regulation output control.

Diagnosis

The seat heater switches contain a diagnostic mode of operation that provides a self check of the system components when activated. The diagnostic information is provided via flash codes from the LED's.

Diagnostic mode activation:
- Switch ignition OFF
- Press and hold the suspect seat heating switch button
- Switch the ignition ON
- Release the heating switch button
- Both LED's illuminate steady indicating the seat heating system is functioning.
- Within 10 seconds the LED will begin flashing the following codes:
- Single flash = Switch faulty due to overheating or short
- Double flash = Short or open in temperature sensor or it's circuit.
- Triple flash = Heating element shorted

Normal operation of seat heating can only be resumed after cycling the ignition key.