Comfort Access System

The Comfort Access System is composed of the part functions
  • Comfort Entry (automatic access control),
  • Comfort Go (automatic driver authorisation) and
  • Comfort Exit.

Comfort Entry

The part function Comfort Entry enables comfortable access to the vehicle by
  • actuating an outside door handle (TAG) or
  • pressing the boot lid/tailgate outside switch.

Comfort Go

The part function Comfort Go enables comfortable starting of the vehicle without the need to insert the remote control in the ignition lock.

Comfort Exit

The part function Comfort Exit enables comfortable locking of the vehicle.

Work on the Comfort Access

Following work on the Comfort Access, in particular on the door handles, it can be necessary to reset the Car Access System. The following two methods are specifically designed for the purpose:
  1. Per service function: Service Functions -> Drive -> CAS -> CAS Reset
  2. Per control unit function under CAS

Note

When the CAS is reset, the lighting of the Start-Stop button is switched off briefly.

Brief description of components

Comfort Access control unit

The Comfort Access control unit is fitted in the right-hand cover in the luggage compartment. The Comfort Access control unit contains the following assemblies:

  • CAN bus interface
  • K-TAGE (outside door handle electronics) bus interface
  • Driver stages for inductive aerials
  • Power supply unit

The Comfort Access control unit contains the fault code memory for the door modules.

Car Access control unit

The Car Access control unit contains the following functions for the Passive Access system:

  • Check of the identifier for access and driver authorisation
  • Fault memory for identifier
  • Activation of the authentication of identifiers through requests from boot switch or starter switch

The Car Access control unit contains the fault code memory for the identifiers.

Comfort Access door module

The door modules of the Comfort Access system consist of the outside door handle electronics (TAGE) and the outside door handle (TAG). The following functions are integrated in each outside door handle:

  • a pull sensor to detect pulling on the outside door handle
  • a pressure sensor to detect pressure on the outside door handle (only E65)
  • a capacitive sensor to detect a hand inserted into the outside door handle
  • a capacitive sensor to detect pressure on the outside door handle (not E65)
  • a transmitter aerial to activate the identifier

The following are implemented in the outside door handle electronics:

  • the link to the K-TAGE bus

    Important: The K-TAGE bus is only looped through in the door control unit!

  • the power supply of the sensors
  • the evaluation of the sensor signals
  • the driver stage for the transmitter aerials

Inductive transmitter aerials

The Comfort Access control unit activates the following 8 transmitter aerials:

  • 4 footwell aerials in the vehicle
  • 1 rear shelf aerial in the vehicle
  • 2 rear aerials in the rear bumper
  • 1 luggage compartment aerial

With the 4 aerials in the doors, there are a total of 12 aerials inside and outside the vehicle.

K-CAN SYSTEM data bus

The K-CAN SYSTEM data bus is the data connection between the instrument cluster and the control units in the chassis and suspension, drive and body sections. Information is exchanged with data telegrams.

Comfort Access sub-bus (K-TAGE)

The K-TAGE bus links the following components of the access and driver authorisation system:
  • the Comfort Access control unit
  • the outside door handle electronics (TAGE) in all four doors
  • the Car Access control unit (CAS) as bus master

Identifiers

Alongside the normal functions of the radio remote control, the identifiers have a radio receiver. The radio receiver enables a response on the part of the identifier to a radio signal from the transmitter aerials of the vehicle.

Main functions

The Comfort Entry and Comfort Go processes only start at a vehicle speed = 0.

Comfort Entry (unlocking the doors)

Actuating an outside door handle (TAG) and pressing the boot lid/tailgate outside switch lead to a request for authentication of the identifier belonging to the vehicle. The request is transmitted across the corresponding transmitter aerial in each TAG or in the bumper. An identifier belonging to the vehicle must be located in the transmission range of the aerial in order to respond to the request. Moreover, the Car Access System (CAS) checks whether the identifier has access authorisation for the vehicle. If this is the case, unlocking of the doors or boot lid/tailgate is triggered. The unlocked component is determined by the subassembly that triggers the authentication process (outside door handle or boot lid/tailgate outside switch).

When the luggage compartment is closed, the luggage compartment aerial requests authentication of the identifier belonging to the vehicle. If an identifier in the luggage compartment replies and there is no other identifier outside the luggage compartment, the luggage-compartment lid is opened again. If another identifier is found outside the luggage compartment, the luggage-compartment lid remains closed. The identifier located in the luggage compartment is blocked as a possible transmitter for the next unlocking of the vehicle.

Comfort Go (starting the vehicle)

When the start button is pressed and the brake pedal is pressed, the vehicle interior aerials search for an identifier located in the vehicle. If an identifier belonging to the vehicle is located in the vehicle, an authentication of the identifier is carried out. If the identifier has start authorisation for the vehicle, the CAS enables the start. The aerials are activated by the Comfort Access control unit.

Comfort Exit (securing the vehicle)

The request to lock the vehicle is activated by pressing an outside door handle. The request is only processed if all the doors are closed. This is followed by an outdoor search for the identifier via the outside aerials. If an identifier is found outside the vehicle, the vehicle is locked. To implement the lockout safety device function, this is followed by a search for an identifier in the passenger compartment. If the identifier that was authenticated at the outside door handle is also detected in the passenger compartment, the vehicle is unlocked again. Other identifiers belonging to the vehicle can remain in the vehicle. In order to inform the driver about this identifier, a corresponding Check Control message is generated.

Unlocking and opening the boot lid/tailgate

The request to open the boot lid/tailgate of the vehicle is triggered by pressing the boot lid/tailgate outside switch. When the vehicle is locked, this leads to a search for an identifier via the rear aerials. The request for the search is sent by the power module via CAN to the CAS and from there to the Comfort Access control unit. This runs the search for the identifier.

Closing rear lid

The lock of the luggage-compartment lid closes mechanically. If the status 'boot lid/tailgate locked' is detected by the power module, the Comfort Access control unit starts a search for the identifier via the luggage compartment aerial. If an identifier in the luggage compartment replies, the CAS control unit transmits the command to open the boot lid/tailgate to the power module. The boot lid/tailgate lift opens the boot lid/tailgate. If another valid identifier is located in the transmission range of the vehicle aerials, the luggage compartment remains closed. The identifier locked in the luggage compartment is disabled for the next opening of the vehicle.

Assignment of an identifier

The assignment of an identifier to a certain aerial of the vehicle is carried out automatically. Here, the aerials of the vehicle are activated successively with delays by radio signals. The time delays create a time window for each aerial in which an identifier found by this aerial can reply. The reply of the identifier in this time window enables allocation of the position of the identifier to a transmitter aerial.

Granting access authorisation/start authorisation

After receipt of a radio signal from the assigned transmitter aerial of the vehicle, the identifier transmitter returns a radio code. If the right data is received in the radio remote control receiver in the vehicle, the functions are enabled. In this way, without actuating the remote control, access authorisation and/or start authorisation are granted.

Misuse protection

The capacitive sensor in the outside door handle is disabled if activated repeatedly. The consequence of this for the customer is a noticeable delay in opening the door. Misuse protection is reset when the central locking system is unlocked, at the latest.

Anti-repeat circuits

If the central locking system switches from the state 'UNLOCKED' to 'LOCKED' 20 times within 2 minutes, no unlocking is possible for approx. 2 minutes. If the anti-repeat circuit is active, the door on the E65 can still be opened, as the electrical opening motor is still activated and this raises the locking pawl. A state can come about, however, whereby the door is open but the locking button is set at LOCKED.

This electrical auxiliary motor reaches the anti-repeat circuit after being activated 50 times. This occurs if the door is opened repeatedly when the vehicle is unlocked.

Initialisation

For the Comfort Access System, the following assemblies must be initialised.
  • Comfort Access control unit
  • Outside door handle electronics, driver's door
  • Outside door handle electronics, rear door on driver's side (if present)
  • Outside door handle electronics, passenger's door
  • Outside door handle electronics, rear door on passenger's side (if present)

Initialising Comfort Access control unit and outside door handles

After replacement of the Comfort Access control unit or an outside door handle, initialisation must be carried out. The initialisation is triggered by switching terminal 0 to terminal R. When terminal R is switched, the Car Access control unit transmits the initialisation automatically to the Comfort Access control unit and this in turn transmits to the outside door handles.

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