Central Locking
Central locking
The functions of the central locking system on the R56 are shared among a number of control modules. The Car Access System (CAS) monitors all the processes in the central locking system. The CAS is the master control module for the central-locking system. The control modules involved in the central-locking system are:
- Car Access System (CAS)
- Footwell module (FRM)
- Junction box electronics (JBE)
Brief description of components
The following components are described for the central-locking system:
- Driver's door lock
- Door contacts
- Remote control
- Central locking button
- Trunk lid/tailgate button
- Car Access System (CAS)
- Footwell module (FRM)
- Junction box electronics (JBE)
Driver's door lock
The driver's door lock cylinder allows manual locking/deadlocking and unlocking of the vehicle. In the event of failure of the motor vehicle electrics, the driver's door can be unlocked using the mechanical key in the remote control.
Door contacts
The signals from the door contact are picked up by the footwell module (FRM). The FRM forwards the signals on the K-CAN to the junction box electronics (JBE).
Remote control
The remote control allows radio-controlled locking and unlocking of the vehicle. The radio signals from the remote control are received by the remote control receiver and transferred to the Car Access System (CAS). The remote control receiver is fitted in the interior rearview mirror.
Central locking button
The central locking button allows the vehicle to be locked/unlocked from the passenger compartment. The following are locked / unlocked: the door, the luggage compartment lid and the fuel filler flap. Double-unlocking and deadlocking are not possible using the central lock button
Trunk lid/tailgate button
The outside boot lid button can be used to open the boot lid if the vehicle is unlocked and stationary.
Car Access System (CAS)
All functions for control of the central-locking system are integrated in the CAS control module. The commands are transferred across the K-CAN to the junction box electronics (JBE).
Junction box electronics (JBE)
The JBE is the executing control module for the central locking system. The JBE handles activation of all the central-locking drives. The JBE consists of the junction box electronics and the power distributor. The junction box is installed under the glove compartment.
Footwell module (FRM)
The footwell module (FRM) evaluates the status of the door contacts. When the vehicle is locked or unlocked with the mechanical key element, the FRM will recognize this request. The FRM sends a message to the CAS on the K-CAN. The FRM is installed at the A-pillar in the footwell of the driver's side.
System functions
The following system functions are described for the central-locking system:
- Lock
- Arrest
- Unlocking
- Crash unlocking
- Forced deadlock release
- Lockout protector
- Anti-repeat circuit
- Automatic relocking
- Voltage monitoring
- Selective release
- Speed-dependent locking
Lock
A locked door cannot be opened from the outside. However, the door can still be opened from the inside. To do this, the door handle must be pulled twice. Locking us executed when
- the doors are closed.
- the central lock button is operated.
- the remote control is operated.
- the door lock in the driver's door is operated.
Arrest
A locked and secured door cannot be opened from the inside or outside. A door is deadlocked if the vehicle is locked via the driver's door lock or the remote control.
Conditions for deadlocking are:
- Terminal R OFF
- Driver's door or front-passenger door was opened
- Driver's door closed
When the vehicle is deadlocked, the anti-theft alarm (DWA) is also primed.
Unlocking
An unlocked door can be opened from the inside and the outside. When the vehicle is unlocked, the anti-theft alarm (DWA) is also deactivated. In the event of failure of the power supply, the driver's door can be unlocked using the mechanical key in the remote control.
Crash unlocking
A crash is detected by the multi-restraint system (MRS). A crash signal is sent to the CAS. The message is sent on the K-CAN. The CAS unlocks the vehicle. All operating points are disabled when there is a crash signal. This prevents unintentional actions of the central locking system from occurring due to short circuits caused by the accident. The central locking system can only be reactivated after a crash once terminal R has been switched off for at least 3 seconds.
Forced deadlock release
When the CAS detects that a remote control is locked in place in the slot, the central locking system is released. The central locking system assumes the "Lock" position. The anti-theft alarm system is also deactivated during forced release.
Lockout protector
To protect the driver against unintentionally locking himself out, all operating points are locked when the driver's door is open. This makes any additional mechanical lock-out protection in the door locks unnecessary.
Anti-repeat circuit
To protect the central-locking drives against overload, the CAS monitors repeat operations. The door, luggage compartment lid and the fuel filler flap are monitored. If there are more than fifteen attempts at activation within one minute, the drives are not unlocked for a certain time.
Automatic relocking
If the central-locking system is unlocked via the remote control and within two minutes no door or the luggage compartment lid is opened, locking takes place automatically.
Voltage monitoring
The function range for the central locking system is specified as being from 9 to 16 volts. Outside of this range, the drives are not activated. If the power supply is interrupted, the state of the central-locking system does not change (anti-theft protection!).
Selective release
With the first unlocking command, only the driver's door is unlocked. The central locking system sets all other doors from deadlock to lock. The DWA is switched off and the doors remain locked. With a second unlocking command, the remaining doors are unlocked. This function can be activated via the Car and Key Memory (depending on the national version).
Speed-dependent locking
The central locking system is automatically locked from a speed of approx. 16 km/h. This function can be activated via the Car and Key Memory.
Notes for Service department
Nearly all Car and Key Memory functions are programmed inside the vehicle itself.
No liability can be accepted for printing or other faults. Subject to changes of a technical nature.