Comfort Access (CA Comfort Access)

Comfort Access System

The Comfort Access System is composed of the part functions
- Comfort Entry (automatic access control),
- Comfort Go (automatic driver authorization) 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 trunk 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-module 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 module
The Comfort Access control module is fitted behind the right-hand cover in the luggage compartment. The Comfort Access control module contains the following assemblies:
- CAN bus interface
- K-TAGE (outside door handle electronics) bus interface
- Driver stages for inductive antennas
- Power supply unit

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

Car Access control module
The Car Access control module contains the following functions for the Passive Access system:
- Check of the identifier for access and driver authorization
- Fault memory for identifier
- Activation of the authentication of identifiers through requests from trunk switch or starter switch

The Car Access control module contains the fault 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 antenna 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 module!

- the power supply of the sensors
- the evaluation of the sensor signals
- the driver stage for the transmitter antennas

Inductive transmitter antennas
The Comfort Access control module activates the following 8 transmitter antennas:
- 4 footwell antennas in the vehicle
- 1 rear shelf antenna in the vehicle
- 2 rear antennas in the rear fender
- 1 luggage compartment antenna

With the 4 antennas in the doors, there are a total of 12 antennas 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 modules 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 authorization system:
- the Comfort Access control module
- the outside door handle electronics (TAGE) in all four doors
- the Car Access control module (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 antennas 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 trunk 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 antenna in each TAG or in the fender. An identifier belonging to the vehicle must be located in the transmission range of the antenna in order to respond to the request. Moreover, the Car Access System (CAS) checks whether the identifier has access authorization for the vehicle. If this is the case, unlocking of the doors or trunk lid/tailgate is triggered. The unlocked component is determined by the subassembly that triggers the authentication process (outside door handle or trunk lid/tailgate outside switch).

When the luggage compartment is closed, the luggage compartment antenna 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 antennas 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 authorization for the vehicle, the CAS enables the start. The antennas are activated by the Comfort Access control module.

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

Closing rear lid
The lock of the luggage-compartment lid closes mechanically. If the status 'trunk lid/tailgate locked' is detected by the power module, the Comfort Access control module starts a search for the identifier via the luggage compartment antenna. If an identifier in the luggage compartment replies, the CAS control module transmits the command to open the trunk 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 antenna of the vehicle is carried out automatically. Here, the antennas of the vehicle are activated successively with delays by radio signals. The time delays create a time window for each antenna in which an identifier found by this antenna can reply. The reply of the identifier in this time window enables allocation of the position of the identifier to a transmitter antenna.

Granting access authorization/start authorization
After receipt of a radio signal from the assigned transmitter antenna 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 authorization and/or start authorization 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.

Initialization
For the Comfort Access System, the following assemblies must be initialized.
- Comfort Access control module
- Outside door handle electronics, driver's door
- Outside door handle electronics, driver's door, rear (if present)
- Outside door handle electronics, passenger's door
- Outside door handle electronics, passenger's door, rear (if present)

Initializing Comfort Access control module and outside door handles
After replacement of the Comfort Access control module or an outside door handle, initialization must be carried out. The initialization is triggered by switching terminal 0 to terminal R. When terminal R is switched, the Car Access control module transmits the initialization automatically to the Comfort Access control module and this in turn transmits to the outside door handles. There is also the possibility to initialize the control modules using a test module: Diagnostic heads / Service functions / Comfort Access / Initialization. The initialization can be checked in this test module.