Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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)
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.