Heated Steering Wheel

The heated steering wheel system consists of the following components:

• A heating filament integrated into the steering wheel cover.
• An NTC temperature sensor, in the filament circuit, to regulate the heating current.
• A push button mounted in the right side MFL key pad.
• The control module located behind the air bag assembly.
• Slip ring assembly for the power and ground supply.
  Fig 1: Identifying NTC Temperature Sensor

  Courtesy of BMW OF NORTH AMERICA, INC.

OPERATION: 

When KL 15 is switched ON, the heated wheel can be switched ON by pressing the button. A green LED illuminates to indicate system operation. Maximum current is supplied and heats the filament to its operating temperature (surface temperature of approximately 90° F). The NTC detects the temperature of the filament and causes the control module to cycle once the wheel is heated. Cycling is carried out with a pulse width modulated signal.

The system is not connected to the diagnostic link, however the control module does monitor operation of the system.

Fig 2: View Of Heated Steering Wheel Circuit Diagram

Courtesy of BMW OF NORTH AMERICA, INC.