Transport mode BMW 528i 1997 E39 Workshop Manual

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51 5-25
Central Lockina and ~nti-~heftl
1
Tilt sensor operation:
1. DWA armed, vehicle level. Tilt sensor sends HlGH sig-
nal to General Module (GM).
2. DWA armed, vehicle tilted. The fluid moves in sensor,
changing resistance value.
HlGH signal changes to
LOW signal. GM activates alarm.
If the vehicle is jacked up or lifted in any way, the angle of the
liquid changes, producing a change in the resistance value.
The sensor signals the GM to activate the DWA alarm. The
sensor resets at the new angle.
This allows the DWA system
to remain armed and to reactivate the alarm if tlie vehicle is
moved again
Locking the vehicle twice within a few seconds will deactivate
the tilt alarm sensor while arming tlie remainder of the sys-
tem. This allows the vehicle to be transported in an armed
state without activating tlie alarm.
Interior protection
The interior motion sensor is mounted in the center of the
headliner panel. Due to the design of the vehicle interior, the
sensor must be installed in the correct direction to ensure
proper operation of the system.
lnterior sensor FIS (1997 - 1999 models)
4 When the alarm system is armed, the FIS sensor emits elec-
tromagnetic waves at
a frequency of 2.45 GHz. As long as
nothing is moving in the vehicle, the waves are reflected
baclc
to the sensor at the same frequency. If a foreign object enters
the vehicle, the frequency of the reflected signal changes.
The sensor detects the changed frequency and triggers the
alarm.
Every time the DWA system is armed, the sensor adapts to
whatever objects might be stationary in the interior. This al-
lows pacltages or objects to be left inside tlie car without ef-
fecting 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 oc-
curring if a small insect is caught in the vehicle.
FIS is switched off when the vehicle is locked two times within
ten seconds. The DWA LED will flash one time for confirma-
tion. This allows the sensor to be switched off to avoid false
alarms when the windows are left open for venting.