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.