Steering column module function - GF54.21-P-4104-04R

Except the switch for variable speeds Tempomat (S40/4)  all switches and modulators that are scanned by the steering column module (N80) are voltage coded. 

This procedure offers the following advantages:

• the reduction of the necessary plug contacts,
• the design is more compact due to smaller plug-in connections,
• contact problems are minimized.

Reading of the voltage codes on the multifunctional steering wheel switch by the steering column modulator: 

Take care to notice the characteristics by the switch voltage coding on the multifunctional steering wheel:

• All multifunctional steering wheel switch contacts are read by the steering column module (N80) over 2  pathways. (The third pathway is for the switch illumination.)

  If the voltage codes sometime meet resistance of varying degrees then a sufficient storage safety is not achievable. For this reason, the buttons are read in as follows:

  The voltage from the steering column (N80) for the testing of the switch constantly changes its polarity. 

  The buttons for the multifunction steering wheel are subdivided into two groups (left and right button group (S110, S111) with associated buttons for fanfares).

  This switch group is by the diode  connect in series, and the poles for both groups differ.

  The test voltage from the steering column module calls up the left or the right switch group depending on the polarity. The switch contact "switches" back and forth between both switch groups  . The actual voltage coding is therefore accomplished within one group of buttons only.

• If in one switch group  on the multifunctional steering wheel more that one switch  is activated at the same time then only the message for a function inside the CAN engine compartment is relayed

  Therefore there are different values  for the different functions in a switch group. The button with the lowest resistance has the highest priority. 

• Switch function values in the left multifunctional steering wheel (S110) : 
  1. Switch function "Fanfare"
  2. Switch function "system selection, back"
  3. Switch function "system selection, forward"
  4. Switch function "back"
  5. Switch function "forward"
• Switch function values in the right multifunctional steering wheel (S111) : 
  1. Switch function "Fanfare"
  2. Switch function "End telephone call"
  3. Switch function "Answer telephone"
  4. Switch function "a"
  5. Switch function "+"

  Example: 

  If the "end telephone conversation" switch and the "a" switch used at the same time then only the activation of the "end telephone conversation" switch is passed on to the CAN!