GF46.11-P-0001LE Steering Wheel Heater (LRH), Function
GF46.11-P-0001LE Steering wheel heater (LRH), function
- with CODE (443) Steering wheel heater
Function requirements, general
^ C. 15R On
^ Interior temperature T less than 30 degrees C
The circuit status is transmitted by the EIS [EZS] control unit (N73) to the front SAM control unit with fuse and relay module (N10/1) via the interior CAN.
Steering wheel heater (LRH) general
The steering wheel rim can be heated with the steering wheel heater (LRH).
The steering wheel heater function is comprised of the following partial functions:
^ Manual on/off function sequence
^ Automatic switch off function sequence
Manual on/off function sequence
The steering wheel heater is switched on or off by turning the steering wheel heater switch (S59/1s2) upwards or downwards. The request from the steering wheel heater is read in by the steering column tube module (N80) and transmitted to the central gateway control unit (N93) via the chassis CAN. This routes the signal on the interior CAN where it is recorded by the front SAM control unit.
Thereupon the electronics of the steering wheel heater (A74) are actuated by the front SAM control unit via a direct line.
At the same time a signal for the function indicator of the steering wheel heater (S59/1e1) in the steering wheel heater switch is transmitted via the interior CAN to the central gateway control unit and from the latter further on to the steering column tube module via the chassis CAN.
The electronics of the steering wheel heater controls the function of the steering wheel heater (R22/4) and energizes the heater coil (R22/4r1).
The heater coil temperature sensor (R22/4b1) measures the surface temperature of the steering wheel rim and passes on this information to the electronics of the steering wheel heater.
The electronics of the steering wheel heater regulates the surface temperature of the steering wheel rim to T = 35 degrees C.
Automatic switch off function sequence
The automatic switch off function is comprised of the following partial functions:
^ Time-controlled switch off
^ Switching off in the event of a hardware defect
^ Switch off in the event of under voltage or over voltage in the on-board electrical system
Time-controlled switch off
The steering wheel heater is automatically switched off by the front SAM control unit.
The timer control of the steering wheel heater is parameterizable via STAR DIAGNOSIS in the front SAM control unit.
Switch off in the event of a hardware defect
If the actuation of the steering wheel heater is detected without a current request or function requirements, the steering wheel heater is switched off and a fault message stored in the fault memory.
Switch off in the event of under voltage or over voltage in the on-board electrical system
If the voltage in the on-board electrical system drops to a value of U less than 10 V the electronics of the steering wheel heater is switched off. If the under voltage is applied for longer than t = 3 min, the indicator lamp of the steering wheel heater switch is also switched off.
If the steering wheel heater function is requested again during the under voltage phase, the indicator lamp lights up for t = 1.5 s and then goes out.
If the voltage in the on-board electrical system rises to a value of U greater than 15.5 V the front SAM control unit switches off the steering wheel heater electronics. The timer control continues running, the steering wheel heater indicator lamp flashes with 50 % brightness.
The threshold value of over voltage is parameterizable via STAR DIAGNOSIS in the front SAM control unit.
It is only possible to switch on the steering wheel heater again, if the permissible voltage in the on-board electrical system applies again for more than t = 15 s.
The voltage in the on-board electrical system is monitored by the front SAM control unit via the battery sensor (B95).
The steering wheel heater function is switched off during the starting process. The timer control does not have an open circuit.
