Electronic Ignition Switch Control Module Task

Task
The electronic ignition switch (EIS) control module acts as communication point between the interior space bus (CAN B), the engine electronic system (ME) and the electronic transmission control (ETC).

Operation of the electric engine/air conditioning fan
The performance of the electric fan engine/air conditioning has infinitely variable control via the engine electronic system (ME) (hardware signal to air exhauster unit).

The variation in cooling is stored in the electronic ignition switch control module (EIS), with identical signal flow for both variations.

The pushbutton control module calculates the set fan RPM and sends the demand via the electronic ignition switch control module (EIS) to the engine electronic system (ME). When operating and with an outside temperature of => 15 °C and a driving speed of <= 70 km/h, a basic ventilation of 20% is demanded.

The engine electronic system (ME) calculates the ventilator RPM in relation to the engine temperature and compares this with the demands from the air conditioning pushbutton control module. The higher value of both is then issued by the hardware in the form of a PWM signal.







Storage of settings in the pushbutton control module
On vehicles fitted with automatic air conditioning some settings of the pushbutton control module, activated before the engine was switched off, are stored in the electronic ignition switch control module. The stored status in the electronic ignition switch control module is then reactivated when the engine is restarted.

The following table shows the different number of stored settings of the automatic air conditioning and the convenience automatic air conditioning:







Specific variation coding for the automatic air conditioning system can be under taken via the diagnostic assistance system (DAS). The following possibilities are available:

- Refrigerant level control
- INACTIVE
- ACTIVE

- Bar indication for blower in automatic mode
- Showing
- Not showing

- REHEAT mode
- Standard
- Anti-icing protection

- Air circulating flap
- VARIABLE
- CLOSED from < 20

- Fresh air / Air circulating flap with automatic air conditioning switched off
- CLOSED
- OPEN

- Auxiliary water pump
- INSTALLED
- NOT INSTALLED

- Comfort closing (tunnel switching)
- MANUAL CLOSING
- AUTOMATIC

- Circulating air convenience mode
- MANUAL CLOSING
- AUTOMATIC

- Comfort operation in circulating air mode
- MANUAL CLOSING
- AUTOMATIC

After contacting the Hotline the following special settings for air conditioning can also be changed by using a time-limited password:
- Manual circulating air control mechanism
- Sun sensor

The pushbutton control module will read these variation codes in via the CAN Bus after ignition ON.

In addition, the following parameters can be changed in the EIS control module.
- National versions
- Left-hand steering
- Right-hand steering
- Engine version
- Vehicle model
- Comfort operation circulating air - 100% circulating air possible
- Yes, hot countries (code 916)
- No (rest of the world)
- Stationary heater installed yes/no