Antitheft and Alarm Systems: Description and Operation
61 09 03 (031) Anti-theft alarm system E60/E61
Introduction
The anti-theft alarm system (DWA) detects and reports attempts at intrusion and tampering with the vehicle. The vehicle interior is monitored by the ultrasonic interior motion detector (USIS). If an attempt is made to break into the vehicle and to enter the interior, the DWA alarm is triggered. A tilt alarm sensor integrated into the siren monitors the vehicle's position. The tilt alarm sensor detects if the vehicle is raised or towed away.
The DWA alarm consists of:
- acoustic alarm via siren (intermittent tone for 30 seconds)
- visual alarm via lighting system (hazard warning lights)
The alarm can be encoded depending on the country concerned.
Brief description of components
The anti-theft alarm system receives input signals from the following components:
- Ultrasonic interior motion sensor
The ultrasonic interior motion sensor uses ultrasonic waves to monitor the vehicle interior. Movement is detected if the reflection (echo) of the ultrasonic waves changes. The sensitivity of the ultrasonic interior motion sensor can be adapted to different conditions (e.g. sliding/tilting sunroof open).
- Tilt alarm sensor
The tilt alarm sensor monitors the vehicle's horizontal position (inclination in longitudinal and lateral directions). The signal from the tilt alarm sensor is evaluated by the microprocessor in the siren. The tilt alarm sensor detects a change in the vehicle position and triggers a DWA alarm.
The following control units are involved in the anti-theft alarm system:
- DWA control unit with ultrasonic interior motion sensor
The DWA control unit forms a unit with the ultrasonic interior motion sensor.
The DWA control unit activates the siren via a single-wire bus. The DWA control unit is connected to the K-CAN.
- Car Access System
The CAS control unit monitors the status of the central locking system. The bonnet contact switch is connected to the CAS control unit. The opening of the bonnet is thus monitored (open or closed). The CAS control unit feeds this signal to the DWA control unit via the K-CAN. The CAS control unit also supplies the flowing signals:
- Boot-lid unlocking via remote control
- Key in ignition starter switch
- Status of convenience opening/closing
- Driver's and front-passenger door modules
The door modules (TMFA and TMBF) supply information about the position of the front power windows. The signal is fed to the DWA control unit via the K-CAN.
In addition, the door modules monitor the door contacts in the front doors.
- Body basic module
The body basic module (KBM) supplies the position of the rear power windows. The signal is fed to the DWA control unit via the K-CAN.
The body basic module also monitors:
- Door contacts in rear doors
- Tailgate contact switch
- Rear window contact switch (E61 only)
- Sliding/tilting sunroof control unit
The SHD control unit supplies information about the position of the sliding/tilting sunroof (or Panorama glass sunroof on the E61). The signal is fed to the DWA control unit via the K-CAN.
- Integrated heating and air conditioning system
The integrated heating and air conditioning system (IHKA) controls the independent ventilation function. The IHKA feeds this signal to the DWA control unit via the K-CAN. The signal for the independent ventilation function is needed to calibrate the sensitivity of the ultrasonic interior motion sensor.
- Independent heater control unit
The SHZH control unit controls the independent heating function. The SHZH control unit feeds this signal to the DWA control unit via the K-CAN. The signal for independent heating function is needed to calibrate the sensitivity of the ultrasonic interior motion sensor.
- Light module
The light module (LM) actuates the lighting system for the visual DWA alarm. The DWA control unit feeds the triggering signal to the light module via the K-CAN.
The following actuators are actuated for the anti-theft alarm system:
- Siren with integrated tilt alarm sensor
The siren with integrate tilt alarm sensor (SINE) emits the acoustic DWA alarm. The DWA control unit activates the siren via a single-wire bus. In addition to the DWA alarm, the siren can also emit an acoustic confirmation signal when the system is primed or disarmed (can be set on the Central Information Display and controller).
- DWA LED
The DWA LED is located on the underside of the interior mirror.
The DWA LED provides a visual indication of the status of the alarm system. The DWA LED is directly actuated by the DWA control unit via a wire. The following displays are possible:
- DWA LED off: DWA is disarmed.
- DWA LED flashes (frequency = 0.5 Hz): DWA is primed.
- DWA LED flashes with a frequency of 2 Hz for 10 seconds and then continues with a frequency of 0.5 Hz: DWA is primed but a door or hatch is not closed or a sensor is defective.
- DWA LED flashes with a frequency of 2 Hz for 5 minutes and then continues with a frequency of 0.5 Hz: alarm is triggered.
- DWA LED lights up for 2 seconds and then flashes with a frequency of 0.5 Hz: the ultrasonic interior motion sensor and the tilt alarm sensor are deactivated.
System functions
The anti-theft alarm system incorporates the following functions:
- Priming/disarming
- DWA alarm triggering (alarm-trigger signal)
- Automatic adaptation of sensitivity of ultrasonic interior motion sensor
- Deactivating interior motion sensor and tilt alarm sensor
- Emergency function for acoustic DWA alarm
- Combined operation with lock cylinder and remote control
Priming/disarming
The anti-theft alarm system is primed when the central locking is locked/deadlocked. Locking/deadlocking requires:
The driver's door to be opened and closed after terminal 15 is switched OFF.
The DWA control unit transmits the "Prime" message to the siren with integrated tilt alarm sensor (SINE) via the local data bus. The siren is then immediately primed. 3 seconds after being primed, the door and hatch contacts are monitored. The condition for this is that the contacts have idle status (doors and tailgate / rear window on E61 closed).
The DWA LED starts flashing and the hazard warning lights flash once as a visual confirmation. Depending on the national version, a short acoustic warning tone may also sound from the siren (see national version).
After the DWA has been primed and all doors and hatches are closed (including the rear window on the E61):
The ultrasonic interior motion sensor starts to map out the interior by means of ultrasonic waves. The interior can be monitored after approx. 20 seconds.
The monitoring of the interior is interrupted if the side windows and/or the sliding/tilting sunroof are closed using the convenience closing function.
Like the interior monitoring, the tilt monitoring does not start until the doors and hatches are closed. When it is activated, the tilt alarm sensor first conducts a 30 second long calibration sequence. Tilt monitoring does not start until the calibration sequence has been completed.
If the luggage compartment is opened during the calibration sequence, the calibration sequence is interrupted. The calibration sequence is then restarted when the luggage compartment is closed again. The monitoring functions of the ultrasonic interior motion sensor and the tilt alarm sensor have priority. If a faulty door or hatch contact is detected, this will automatically be assumed to be closed.
The anti-theft alarm system is disarmed when the central-locking system is unlocked. The DWA LED stops flashing and the hazard warning lights flash twice as a visual confirmation. Depending on the national version, a short acoustic warning tone (dual tone) may also sound from the siren (see national version).
The luggage compartment can also be unlocked and opened with the remote control without the alarm being triggered, even if the alarm system is activated. When the luggage compartment is opened, the interior monitoring and tilt monitoring are deactivated. The interior monitoring and tilt monitoring are reactivated as soon as the luggage compartment is closed again.
DWA alarm triggering (alarm-trigger signal)
The DWA alarm is triggered if an alarm status is detected while the alarm system is activated. The following will trigger the DWA alarm:
- Forced opening of a door: Bus signal from door contact (via door modules or body basic module)
- Forced opening of luggage compartment: Bus signal from tailgate contact switch (via body basic module)
- Forced opening of rear window on E61: Bus signal from rear window contact switch (via body basic module)
- Forced opening of bonnet: Bus signal from bonnet contact switch (via CAS control unit)
- Movement in interior: Signal from ultrasonic interior motion sensor
- Vehicle in inclined position: Signal from tilt alarm sensor
- Open circuit in local data bus (between DWA control unit and siren)
- Monitoring of vehicle battery:
- On-board supply voltage drops from 7.5 to 6.5 volts within 40 minutes
- Battery positive cable cut through
- On-board supply voltage > 18 volts
When a DWA alarm is triggered, the DWA control unit activates the siren via the local data bus. At the same time, the DWA control unit transmits a message through the K-CAN. The light module activates the visual alarm via the lighting system.
The siren can trigger an acoustic alarm if it is separated from the vehicle electrical system by manipulation while the DWA is activated.
If the local data bus is separated as this happens, the DWA control unit will also trigger the visual alarm.
A DWA alarm will immediately be cancelled if:
- The DWA is disarmed (e.g. with the remote control)
- The message "key is in ignition lock" is detected (from CAS)
Automatic adaptation of sensitivity of ultrasonic interior motion sensor
To prevent false alarms, the sensitivity of the ultrasonic interior motion sensor is adapted to the vehicle's conditions. To do this, the DWA control unit (and thus also the ultrasonic interior motion sensor) receives the following information via the K-CAN:
- Position of front power windows (door module, driver and front passenger)
- Position of rear power windows (body basic module)
- Position of sliding/tilting sunroof (sliding/tilting sunroof control unit)
- Status of comfort functions, e.g. convenience opening (Car Access System)
- Independent ventilation function (integrated automatic heating/air conditioning system)
- Independent heating function (independent heater control unit)
The range (sensitivity) of the ultrasonic signals is adapted. The positions of the side windows and the sliding/tilting sunroof are evaluated by the DWA. If no position value is available, a less sensitive setting is selected.
If the DWA is activated and a comfort function is executed (e.g. convenience closing using remote control):
- If the position of the side windows or sliding/tilting sunroof is changed, the interior monitoring function is deactivated for as long as the closing procedure runs.
- After the closing movement has been completed, or at most after 25 seconds:
the positions of the side windows and sliding/tilting sunroof are re-evaluated and the sensitivity adapted.
The switching-on of the independent ventilation or independent heating system is also monitored to prevent false alarms (movement in vehicle interior caused by airflow).
Deactivating interior motion sensor and tilt monitoring
It may be advisable to deactivate the tilt monitoring and interior motion sensor under the following conditions:
- when the vehicle is being transported (e.g. rail, ferry)
- When the vehicle is parked in a two-level garage
- When persons or animals remain in the vehicle
The tilt monitoring and interior motion sensor are deactivated when the command "lock/deadlock" is executed twice within the space of 10 seconds (e.g. with the remote control).
The DWA LED indicates the deactivation by lighting up for 2 seconds.
The ultrasonic interior motion sensor and the tilt alarm sensor can also be permanently deactivated (see Car and Key Memory).
Emergency function for acoustic DWA alarm
If the siren fails during an alarm, or if the local data bus is interrupted, the acoustic alarm is emitted from the fanfare horn. To do this, the DWA control unit transmits a message to the steering column switch cluster (SZL).
Combined operation with lock cylinder and remote control
The alarm system can be primed and disarmed by either the door lock or the remote control (= combined operation). In some countries, insurance requirements prohibit such combined operation.
In the event of the combined operation failing, the alarm system can still be primed at the door lock, but cannot be disarmed at the door lock. Disarming is only possible with the remote control. The function of the combined operation can be encoded in the CAS control unit.
Notes for service staff
Service staff should note the following points:
- General information:
- Diagnostics: ---
- Encoding/programming: ---
- Car and Key Memory:
National versions
DWA alarm output on different national versions
Differing registration requirements and other individual settings made with the Car & Key Memory can mean different alarms:
Panic mode with national versions US and Japan
Panic mode enables the DWA alarm to be triggered to attract attention in the event of a threat from the outside or an accident.
If panic mode is encoded (instead of boot-lid unlocking):
Panic mode is triggered with the remote control. To do this, the special button has to be pressed for 3 seconds (special button = EURO boot-lid unlocking button). Panic mode can be triggered regardless of the DWA status (primed/disarmed). Panic mode is ended when any button on the remote control is pressed.
If the siren fails during panic mode, the acoustic alarm is emitted from the fanfare horn (emergency function).
The duration of the alarm in panic mode is unlimited (until the vehicle battery is flat).
Subject to alteration due to misprints, errors and technical modifications.