Electronic ignition switch control module, purpose - GF80.57-P-4102-03T

Purpose/scope of function 

The EIS control module (N73) is included in the vehicle network and serves as a gateway of data relevant for drive authorization between the passenger compartment CAN bus and the engine compartment CAN bus. It handles the complete bi-directional data flow to the remote control key (A8/1).

The EIS control module (N73) encrypts and decrypts data and performs an authentication test.

The control of the shift-lock function (automatic transmission) is also taken over by the EIS control module (N73)

Overview 

• Gateway of data relevant for drive authorization between passenger compartment CAN bus and engine compartment CAN bus
• Encrypted bi-directional IR communication to key hash coding.
• Energy transmission to remote control key (A8/1).
• Transmission of the authentication values for enabling electric steering lock control module (N26/5) and engine control module with DAS 3 drive authorization system.
• Limit switch for circuit 15 and circuit 15R.
• Driver output for actuation circuit 50.
• Rotation angle-dependent activation of individual signals.
• Position and hold remote control key (A8/1) in unturned position
• Lock remote control key (A8/1) in turned position
• Rotation lock of remote control key (A8/1) by locking solenoid.
• Shift-lock function in combination with automatic transmission actuation of rotation angle recognition of remote control key (A8/1).
• Return from start to drive position
• Close key opening when remote control key is removed (A8/1).

Drive and access authorization 

The vehicle is locked and unlocked by the radio/infrared remote control.

The RF antenna is integrated in the rear window. The antenna module demodulates the HF signals and relays them to the rear SAM control module with fuse and relay module (N10/2). From there data is relayed to the EIS control module (N73) via the passenger compartment CAN bus.

The IR receiver is installed in the driver's door handle. Demodulation of the IR signals is accomplished by the door control module, the information is relayed to the EIS control module (N73) via the passenger compartment CAN bus.

The EIS control module (N73) performs authentication and actuates the central locking.

The vehicle cannot be started until after successful IR communication in the EIS control module (N73). When the remote control key (A8/1) is inserted into the EIS control module (N73), the electronic circuitry is waked up by the "Sleep mode" and the remote control key (N8/1) is supplied with energy from the EIS control module (N73). Identification of the remote control key (A8/1) is accomplished with bi-directional data exchange. The EIS control module (N73) releases the selector lever lock (automatic). Then the participating control modules are enabled via the passenger compartment CAN bus

Following successful communication: 

• Lock solenoids enabled.
• Switch on remote control key position recognition.
• Wake up passenger compartment CAN bus, remote control key (A8/1) turned approx. 90° - "Radio setting" (setting 1).
• Actuate circuit 15R.
• Output of circuit 15R status to passenger compartment CAN bus, remote control key (A8/1) turned another 30° - "Ignition" (setting 2).
• Circuit 15 actuated.
• Output of circuit 15 status to passenger compartment CAN bus and engine compartment CAN bus as well as circuit 15X on passenger compartment CAN bus.
• Encrypted release of engine control
• Message transfer from engine compartment CAN bus to passenger compartment CAN bus
• Message transfer from passenger compartment CAN bus to engine compartment CAN bus, remote control key (A8/1) turned another 30° - "Engine start" (setting 3).
• Actuation of starter relay via engine control module.
• Status transfer circuit 50 passenger compartment CAN bus to engine compartment CAN bus.
• The transfer from circuit 15X to passenger compartment CAN bus is interrupted during circuit 50 ON

Take vehicle out of operation 

• Turning remote control key (A8/1) back to the left stops the engine.
• Circuit 15R remains switched on in key position 1.
• The mechanical shift-lock function prevents turning back the remote control key (A8/1) to the 0 position when the selector lever is not in the "P" position (vehicles with automatic transmission).
• The remote control key (A8/1) can be removed in key position 0.
• The EIS control module (N73) can request a new hash value when restarting without removing the remote control key (A8/1).