GF46.11-P-0001R Steering Wheel Heater (LRH), Function

GF46.11-P-0001R Steering wheel heater (LRH), function
- with CODE (443) Steering wheel heater

Component Identification:

Function

The steering wheel heater can be used to heat the steering wheel to provide a more comfortable and secure grip in cold weather. The steering wheel heater is switched on and off by a rotary function of the steering wheel heater switch. The position of the steering wheel heater switch is read in by the electronics in the steering column tube module (N80) and placed on the CAN Class B.

There are 3 positions for the steering wheel heater:
^ Center position
^ Turning upwards
^ Turning downwards

For the function indicator a red function LED is integrated in the steering wheel heater switch. The function indicator is switched off in the event of a defect in the steering wheel heater.

The DC/DC converter control unit (N99) leads voltage to the steering wheel heater electronics fitted in the steering wheel. This energizes the heating coil in the steering wheel rim in order to heat up the steering wheel and regulates the steering wheel heater to the target temperature of approx. 28 degrees C at the steering wheel surface.

The information whether heated or an internal diagnosis (steering wheel self-test) should be carried out, is conveyed to the steering wheel heater electronics by different voltage levels at its input.

Tasks of steering wheel heater electronics:

^ Energizing the heater coil in the steering wheel rim
^ Measuring the surface temperature of the steering wheel rim via the integrated temperature sensor
^ Carrying out the diagnosis for the heater coil and the temperature sensor in the steering wheel rim.

Two power settings are possible:

^ Heating with minimal power (power supply 42 V)
^ Heating with maximum power (power supply 48 V)

An increase from 12 V to 42 V or 48 V is necessary so that the steering wheel heater can be supplied with a power of approx. 100 W.

In order to enable rapid heating up, the heater coil is supplied with 48 V when switched on.

In order to protect it from overheating, the time is limited to 7 minutes. After this minimum power is applied to the heater coil (power supply 42 V).

The maximum permanent heating time is 24 minutes. After this the heater coil is switched off. The system is controlled and monitored by the DC/DC converter control unit (N99).

The interior temperature is reported from the overhead control panel control unit (N70) to the DC/DC converter control unit via CAN class B (N99). The DC/DC converter control unit (N99) evaluates the interior temperature signal to protect the heating spiral.