Steering wheel heater (LRH), function - GF46.11-P-0001TA

MODELS 211.0/2/6 as of 1.6.04 with CODE (443) Steering wheel heater

15.03.07

The document has been updated to this date and will no longer be subject to revision.

Fig 1: Steering Wheel Heater (LRH) Function Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

General

In order to make hand contact more comfortable and safer at low temperatures, the steering wheel can be heated up via the steering wheel heater (LRH).

Operation takes place via the steering wheel heater switch (S59/1s2), control is taken over by the HS [SIH] and seat ventilation control unit (N25/7).

Function requirements

Circuit 15R or circuit 15 ON
Interior temperature < 30 °C

Switch on steering wheel heater (LRH)

Rotate the steering wheel heater switch (S59/1s2) upwards.
The signal is read in by the steering column module (N80) and transmitted via the CAN-B (CAN-B) to the HS [SIH] and seat ventilation control unit (N25/7).
The heater coil (R22/4r1) is supplied with voltage by the HS [SIH] and seat ventilation control unit (N25/7) via the steering wheel heater electronics (A74).
The temperate of the steering wheel rim is measured by the steering wheel heater electronics via the heater coil temperature sensor (R22/4b1) (A74) and used for the control (target temperature approx. 35 °C).

Function indicator

The activated steering wheel heater (LRH) is displayed by the steering wheel heater function indicator (S59/1e1) in the steering wheel heater switch (S59/1s2).

Switching off steering wheel heater (LRH) manually

Turn the steering wheel heater switch (S59/1s2) downwards.
The signal is read in by the steering column module (N80) and transmitted via the CAN-B (CAN-B) to the HS [SIH] and seat ventilation control unit (N25/7).
The HS [SIH] and seat ventilation control unit (N25/7) deactivates the steering wheel heater (LRH).

The steering wheel heater function indicator (S59/1e1) in the steering wheel heater switch (S59/1s2) goes out.

Switching off the steering wheel heater (LRH) automatically

Once the maximum heating time has elapsed (continuous heat mode for 15 minutes) the HS [SIH] and seat ventilation control unit (N25/7) is shut off.
The steering wheel heater function indicator (S59/1e1) goes out.
The HS [SIH] and seat ventilation control unit (N25/7) is shut off at an interior temperature higher than 30 °C.
The steering wheel heater function indicator (S59/1e1) remains active.

Abort conditions

During the engine starting process.
The steering wheel heater function indicator (S59/1e1) remains active.
In the event of undervoltage or overvoltage.
The steering wheel heater function indicator (S59/1e1) flashes at 1.5 Hz and 50 % brightness.

Reading in the steering wheel heater switch (S59/1s2):

The position of the steering wheel heater switch (S59/1s2) is read out by the steering column module (N80) and placed on CAN-B (CAN-B). As long as the steering wheel heater switch (S59/1s2) is operated (turning up or down), the corresponding position is transmitted cyclically. The center position of the steering wheel heater switch (S59/1s2) is not transmitted by the steering column module (N80).

The interior temperature is transmitted by the AAC [KLA] control and operating unit (N22) or by the comfort AAC control and operating unit (N22/7) via the CAN-B (CAN-B).

Circuit 15R is switched off.
The timer control continues running for 5 minutes with circuit 15C < > On. If within this period circuit 15R is switched on again, the steering wheel heater (LRH) is also activated again.

Steering wheel heater (LRH), block diagram		GF46.11-P-0001-02TA
Steering wheel heater (LRH), location of components		GF46.11-P-0001-03TA
Steering wheel heater switch, location/task		GF46.11-P-4001T
Steering wheel heater electronics, location/task		GF46.11-P-4003T
Heated seats/seat ventilation control unit, location/task		GF91.30-P-3005T
Steering column module, location/task		GF54.21-P-4125T
Electronic ignition switch control unit, location/task		GF80.57-P-4120T
Control and operating unit for automatic air conditioning, location/task	On vehicles without code (581b) comfort automatic air conditioning	GF83.40-P-2180T
Control and operating unit for comfort automatic air conditioning, location/task	On vehicles with code (581b) comfort automatic air conditioning	GF83.40-P-2181TT