Central Locking

Central Locking

From a functional point of view, central locking system on the BMW 1-Series and 3-Series is divided among several control modules. The Car Access System (CAS) monitors all the processes in the central locking system. The CAS control module is the master control module for the central-locking system. The control modules for the central locking system are:
- Car Access System (CAS)
- Footwell module (FRM)
- Junction box electronics (JBE)

The CAS control modules use the prompts from various operating points (e.g. lock cylinder, remote control, comfort access) to decide what needs to be done:
- Locking/deadlocking the central locking system
- Unlocking the central locking system

Brief description of components
The following components supply an input signal for the central locking system:

Door lock cylinder
The door lock cylinder allows manual locking/deadlocking and unlocking of the vehicle. If the vehicle electrics should fail, the driver's door can be unlocked manually with the key (mechanical key element in the remote control).

Remote control
The remote control allows the vehicle to be locked/deadlocked via radio (antenna interface). The radio signals from the remote control are received by the FBD receiver (receiver for remote control) and transferred to the CAS control module.

The remote control receiver is integrated in the antenna amplifier.

On the Convertible, the remote control receiver is fitted in the interior mirror.

Center lock button
The central locking button enables manual locking/deadlocking and unlocking of the vehicle from the inside. The fuel filler flap is not locked. On the Convertible, the glove box and the storage compartment in the centre console are not locked.

Hotel position switch (US version)
The hotel position switch is installed in the glove box. The hotel position switch decouples the tailgate from the central locking system. When hotel position is selected (locked or unlocked), the setting of the hotel position switch is detected.

Interior luggage compartment lid / tailgate button (US version)
The interior luggage compartment lid / tailgate button on the A-pillar in the driver's footwell allows the luggage compartment lid / tailgate to be opened when the vehicle is unlocked and stationary (hotel position not selected).

Exterior luggage compartment lid / tailgate button on luggage compartment lid
The exterior luggage compartment lid / tailgate button on luggage compartment lid allows the luggage compartment lid to be opened while the vehicle is unlocked and stationary (hotel position not applied).

Trunk lid / tailgate lock
The luggage compartment lock allows the luggage compartment to be mechanically opened (hotel position not selected).

Rear window button
The rear window button can be used to open the rear window if the vehicle is unlocked and stationary. The rear window switch is integrated in the rear window wiper.

The following control modules are involved in the central locking system:

CAS: Car Access System
All the rules for controlling the central locking are integrated in the CAS control module. The commands are transferred via the K-CAN.

JBE: Junction Box Electronics
The junction box electronics are the executing control module for the central-locking system. The JBE handles activation of all the central-locking drives. The junction box consists of the junction box electronics and the electrical distribution centre. The junction box is installed under the glove compartment.

FRM: Footwell Module
The footwell module evaluates the status of the Hall sensors in the door contacts. When the vehicle is locked or unlocked with the mechanical key element, the footwell module will recognize this request. The footwell module transmits a message on the K-CAN to the CAS control module (CAS: Comfort Access System). The footwell module is installed at the A-pillar down in the footwell of the driver's side.

The following actuators are activated by the central locking system:

Door lock
The door locks comprise:
- 2 drives with gearing
- Hall sensors as door contact

Drives in the door locks
There are 2 drives in each door lock. The locking mechanism can be brought into the following position by the drives:
- Lock: door can still be opened from the inside
- Deadlock: Door can be opened neither from the outside nor from the inside.
- Unlock: door can be opened from the inside and outside

Drive for fuel filler flap
The drive locks/unlocks the fuel filler flap.

Drive for the luggage compartment lock
The drive unlocks the luggage compartment lid.

Drive for rear window lock
The drive unlocks the rear window.

Drive for electrically locking glove box
If central double-locking is activated via the central locking system, the door lock cylinder or Comfort Access, the drive blocks the opener of the glove box.

In this situation, it is only possible to open the glove box with the mechanical key.

If the glove box was locked with the mechanical key, it can only be opened again with the mechanical key.

Drive for electric locking of stowage compartment in centre console
The drive locks the storage compartment in the centre console. In the event of a flat or defective battery, the storage compartment in the centre console can be released in an emergency using a cable assembly.

Unlocking drive for the roller cover
There is an unlocking drive on the left and right-hand sides of the D-pillar. To unlock the roller cover, the unlocking drivers are actuated for about 2 seconds by the junction box electronics.

System functions
The central locking system incorporates the following functions:
- Lock
- Arrest
- Unlocking
- Hotel setting
- Crash unlocking
- Forced deadlock release
- Lockout protector
- Anti-repeat circuit
- Automatic relocking
- Voltage monitoring
- Selective release
- Speed-dependent locking
- Locking the fuel filler cap

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 is performed in the following ways:
- Operating the central locking button (condition: front doors must be closed)
- Operation via the driver's door lock cylinder or the remote control, where the conditions for deadlocking are not fulfilled (see "Deadlocking").
- Driver's door closed

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 cylinder or the remote control. Conditions:
- Terminal 30B OFF
- Driver's door or passenger's 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.

Hotel position (US version)
When the hotel position is selected, the luggage compartment lid also stays locked after the vehicle is unlocked. For hotel position to be selected, the setting of the hotel position switch is detected.

Crash unlocking
A crash is detected by the ACSM control module. A crash signal is transmitted by the CAS control module. The message is sent on the K-CAN. The CAS control module 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 30B has been switched off for at least 3 seconds.

(ACSM stands for "Advanced Crash Safety Module", also known as the crash safety module)

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 (doors, tailgate, fuel filler flap, rear window, glove box and stowage compartment in the centre console) against overloading, the CAS monitors repeat operation. If there are more than 15 attempts at activation within one minute, the drives are not unlocked for a certain time.

Automatic relocking
If the central locking system is unlocked using the remote control and no door or luggage compartment lid is opened within 2 minutes, the vehicle is automatically locked again (locked and secured). This function can be activated via the personal profile.

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 in the Personal Profile (depends on national version concerned).

Speed-dependent locking
The central locking system is automatically locked from a speed of approx. 16 km/h.

This function can be activated in the Personal Profile (depends on national version concerned).

Locking the fuel filler cap
The fuel filler flap is only locked when the central locking system is set to deadlock. This function can be activated in the Personal Profile (depends on national version concerned).

Notes for Service department

General information
Nearly all Car and Key Memory functions are programmed inside the vehicle itself. (See "Personal Profile" in the Owner's Manual: individual settings for a maximum of 3 remote control modules via the display in the instrument cluster or via the Central Information Display)

Country-specific versions

National version US
The glove box is electrically locked. Reason: Knee airbag fitted in glove box lid. In order to transmit the forces that are released when the airbags are triggered, the glove box lid is bolted on both sides when it is closed.

When the opener is lifted slightly to open the glove box, a microswitch transmits a signal to the junction box electronics (JBE). The JBE briefly actuates the unlocking drive in the glove box. The unlocking drive retracts the 2 locking bolts. The glove box lid can then be opened again. After a short time, the unlocking drives are de-energized and the locking bolts extend again. The locking bolts have an angled area at the end. This has the effect of mechanically pushing the locking bolts onto a spring when the glove box lid is closed. When the glove box lid is closed, the spring pushes the locking bolts back out, locking the glove box.

No liability can be accepted for printing or other faults. Subject to changes of a technical nature