Anti-Theft (DWA) System

Anti-Theft (DWA) System

Purpose of the System
The DWA alarm system offers vehicle protection by monitoring the doors, hood, interior, luggage compartment and vehicle tilting. When activated, DWA deters theft by sounding an alarm siren for 30 seconds, flashing the low beam headlights (high beam on Xenon equipped models) and four way flashers for 5 minutes.

The control electronics for DWA are integrated in the general module. The DWA - LED indicator is located in the rear view mirror (E38 in the top center IHKA grille).




The system is "armed/disarmed" from the driver's door lock cylinder, remote transmitter or luggage compartment lock cylinder. The alarm is immediately deactivated when disarmed with the key in the driver's door lock cylinder (may be deactivated in Conversion) or remote transmitter.

The GM utilizes existing components and/or circuits as part of the DWA system:
- Door latch switch/sensor contacts (door open/closed).
- Trunk lid switch contact (monitored for closed trunk).
- Trunk lock key position switch (located on the trunk lock, this switch signal prevents DWA from activating if armed when the trunk is opened with the key).
- Hood switch (monitored for closed hood, located under the hood).
- DWA status LED (part of rear view mirror).

The additional components required are:
- Interior Sensor
- DWA Siren
- Tilt sensor

System Components

Interior Sensor FIS (up to 99 MY)




The interior sensor is mounted in the center of the headliner panel. Due to the design of the vehicles interior, the sensor is uni-directional and must be installed in the proper direction to ensure proper operation of the system.

When the alarm system is armed, the sensor emits electromagnetic waves at a frequency of 2.45 GHz. As long as nothing is moving in the vehicle, the waves as bounced back to the sensor at the same frequency. The sensor monitors these bounced back waves as an indication that nothing is disturbed within the vehicle.

If a foreign object enters the vehicle, the frequency of the bounced back signal changes. The sensor monitors the changed frequency and triggers the alarm.




Every time the DWA system is armed, the sensor adapts to what ever objects might be stationary in the interior.

This allows packages or objects to be left inside the car without effecting the operation of the system. The sensitivity of the sensor is set so that the moving object must be at least as large as a bumble bee. This prevents a false alarm from occurring from small insects that might be caught in the vehicle.

The FIS is switched OFF when the vehicle is locked two times within ten seconds. The LED will flash one time for confirmation. This allows the sensor to be switched OFF to avoid false alarms when the windows are left open for venting.

Interior Sensor UIS (after 99 MY)
Similar to the FIS, the UIS monitors the vehicle interior for motion. The UIS uses ultrasonic sound waves instead of microwaves (less suceptable to magnetic interference). The UIS is a combined transmitter and receiver.




The interior sensor is mounted in the center of the headliner panel. Due to the design of the vehicles interior, the sensor is uni-directional and must be installed in the proper direction to ensure proper operation of the system (trim cover ensures directional installation).

Every time the DWA system is armed (signal STDWA), the sensor adapts to what ever objects might be stationary in the interior. The sensor emits ultra sonic waves in a programmed timed cycle. It receives echos of the emitted waves.

The UIS amplifies the received sound wave signals and compares them with the transmitted waves. The UIS also checks the incoming echos for background hiss (wind noise through a partially open window) and adapts for this.
- If the echos are consistently similar, no movement is detected.
- If the echos are altered, (inconsistent), the UIS determines motion in the interior compartment.

If motion is detected, the UIS changes to a constant cycle and the echo is compared again. If the inconsistency is still present the UIS sends the activate siren signal (INRS) to the GM.

The UIS is switched OFF when the vehicle is locked two times within ten seconds. The LED will flash one time for confirmation. This allows the sensor to be switched OFF to avoid false alarms when the windows are left open for venting.

Tilt Sensor (Liquid Type - E38/E39 to 97 MY)




The Tilt Sensor consists of a conductive liquid chamber, a processor board and metal probes (located in the luggage compartment). The probes are submersed in the liquid and produce a resistance value dependent on the tilt of the sensor (angle of vehicle). This resistance value becomes the static point when the DWA System is armed.

If the vehicle is jacked-up or lifted, the angle of the liquid changes producing a change in the resistance value. The sensor recognizes this change and signals the GM to activate the DWA alarm.

The resets at the new angle. This allows the DWA to remain armed and re-activate the alarm if the vehicle is moved again.

As with the interior sensor, the tilt sensor is also switched Off when the vehicle is locked two times within ten seconds. The LED will flash one time for confirmation. This allows the sensor to be switched OFF for transportation purposes.

Tilt Sensor (Electronic Type from 98 MY)
Located in the luggage compartment area, the tilt sensor is an electronic sensing device with the sole purpose of monitoring the vehicle's parked angle when DWA is armed.

The sensor requires three signal wires to function:




- KL 30 - Constant battery voltage
- Signal "STDWA"; switched ground input signal provided by the GM indicating BWA armed/disarmed status
The tilt sensor is used as a splice location for the STDWA signal to the Siren and UIS interior protection sensor.
- Signal "NG"; switched ground output signal provided to the GM. The signal is used for two purposes,
1. As a momentary acknowledgment that the tilt sensor received STDWA and is currently monitoring the vehicle angle.
2. If the tilt sensor detects a change in the vehicle's angle when DWA is armed, signal NG is switched to inform the GM to activate the siren.

When the tilt sensor receives the STDWA signal from the GM it memorizes the vehicle's parked angle. The angle of the vehicle is monitored by the solid state electronics. Once armed, if the angle changes, the tilt sensor provides a switched ground signal to the GM to activate DWA.

As with the interior sensor, the tilt sensor is also switched OFF when the vehicle is locked two times within ten seconds. The LED will flash one time for confirmation. This allows the sensor to be switched Off for transportation purposes.

Glass Breakage Sensors (Early E38 - before FIS Sensor)
The door windows (including the rear quarter glass wire loop) are monitored by inductive sensors mounted on the inside of the door behind.the trim panel. A closed window is recognized by a magnetic plate on the glass lining up with the sensor.

If the glass is broken, the plate falls away and the signal from the sensor changes and the GM will activate the alarm.

Alarm Siren
The alarm siren is mounted in the rear wheel well, behind the inner wheel housing cover (early E38 used an alarm horn).The E53 alarm siren is located in the left side of the engine compartment.




The siren contains electronic circuitry for producing the warning tone when the alarm is triggered. The siren also contains a rechargeable battery that is used to power the siren when the alarm is triggered.

The rechargeable battery will allow the siren to sound if it or the vehicle's battery is disconnected. The siren battery is recharged, from the vehicle's battery, when the alarm is not in the armed state.




The siren has four wires connecting it to the system; KL 30, KL 31, activate siren signal (SIRENE) and the arm/disarm signal (STDWA).

The arm/disarm output signal from the GM is provided to the Tilt sensor, FIS/UIS sensor and the siren. The arm/disarm signal is a switched ground that signals the components of an armed/disarmed status.

The activate siren signal to the siren is high whether BWA is armed or disarmed. If a monitored input activates the alarm, the high signal to the siren is switched to a 50% duty cycle at the GM. The control circuitry in the siren activates the siren driver.

If the DWA is armed and the battery is disconnected the siren recognizes the normally high "SIRENE" signal as suddenly going low, the siren is activated.

System Components: Inputs - Processing - Outputs




Principle of Operation

DWA Arming/Disarming
- The DWA is armed every time the vehicle is locked from the outside with the door lock cylinder or FZV key.
- The DWA LED flashes as an acknowledgment along with the exterior lights and a momentary chirp from the siren.
- The GM monitors all required input signals for closed status (door closed, luggage compartment closed, etc.) The inputs must be in a closed status for a minimum of 3 seconds for the GM to include them as an activation component. If after 3 seconds any input signal not in the closed status is excluded (this is acknowledged by the DWA LED) preventing false alarm activations. The hood switch can be "lifted to the service position to test the alarm with the hood open.
- If the DWA is armed a second time within 10 seconds, the tilt sensor and interior protection sensor are excluded as alarm activation components. This function is useful if the vehicle is transported on a train or flat bed truck to prevent false alarm activations.
- While armed, the trunk can be opened with out the alarm being triggered as follows:
- If opened with the trunk remote button via the FZV, the GM prevents the alarm from activating. (This feature is customizable under the Car Memory function).
- If opened with the key at the trunk lock cylinder the trunk key position switch signals the GM and in the same manner prevents the alarm from activating.
In either case, when the trunk is returned to the closed position, it is no longer considered as an activation signal.

Panic Mode Operation: When the trunk button is pressed and held, the GM is signaled to activate the siren for the Panic Mode. The panic mode is function with either an armed or disarmed DWA system.

Emergency Disarming: Emergency disarming occurs automatically if a key is used to turn the ignition switch on and the EWS accepts it. The EWS signals the GM to unlock the doors and deactivate the DWA.

Alarm Indication
When the alarm is triggered, the siren will sound for 30 seconds. At the same time the low beam headlights (high beams on Xenon equipped vehicles) and four way flashers for 5 minutes. The GM signals the LCM via the bus system to flash the lights.

Following an alarm activation, the system will reset and activate again if further tampering occurs.

DWA LED Status:

DWA STATUS DWA LED CONDITION
Disarmed OFF
Armed Continual slow flash
Armed with one or more monitored Rapid flash for 10 seconds,
inputs not in closed position then continual slow flash.
(ie: trunk not fully closed, etc)
Alarm activated Rapid flash for 5 minutes,
then continual slow flash.
Rearmed in less then 10 seconds. ON for 1 second
Disarmed after activated alarm Rapid flash for 10 seconds, then OFF.