1995 BMW 740il 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.
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Interior Sensor UIS (after 99 MY):Similar to the FIS, the UIS monitors the vehicle interi-
or for motion. The UIS uses ultrasonic sound wavs 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 pro-
grammed timed cycle. It receives echos of the emitted waves.
The UIS amplifies the received sound wave signals and compares them with the transmit-
ted 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 com-
partment.
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.
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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 resis-
tance value. The sensor recog-
nizes 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 comparment area,
the tilt sensor is an electronic sensing device with the sole purpose of monitoring the vehi-
cle's parked angle when DWA is armed.
The sensor requires three signal wires to func-
tion:
• KL 30 - Constant battery voltage
• Signal "STDWA"; switched ground input sig-
nal provided by the GM indicating DWA
armed/disarmed status.
The tilt sensor is used as a splice location for
the STDWA signal to the Siren and UIS int-
erior protection sensor.
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• 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 cur-
rently 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 (includ-
ing 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 warn-
ing 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.
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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 DWA is armed or disarmed. If a mon-
itored 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.
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SIRENE
STDWA
97 MY E38 Shown

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 com-
partment closed, etc.) The inputs must be in a closed status for a minimum of 3 sec-
onds 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 posi-
tion to test the alarm with the hood open.
• If the DWA is armed a second time within 10 seconds, the tilt sensor and interior pro-
tection 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 sig-
nals 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 con-
sidered 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.
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Sunroof
Purpose of the System
When the ignition key is in accessory or “on”
position press the switch or slide it to the desired
direction to lift (2), open (1) or close the sunroof.
When lifting, the headliner retracts several inch-
es. The sunroof can continue to operate after
the ignition has been switched off as long as one
of the front doors has not been opened.
Mechanically, the sunroofs are similar in design.
Some vehicles are equipped with the steel roof
while others are equipped with the glass (moon)
roof.
The anti-trap feature of the sunroof uses a hall
sensor to detect obstructions while the sunroof
is closing. The initialization procedure must be
carried out to allow the sunroof to operate in the
opening direction and allow the anti-trap feature
to function.
The anti-trap is shut down 4mm
prior to full closed and during the tilt closing
function.
System Components
Sunroof Switch:Mounted in the sunroof motor trim cover, the switch provides coded
ground signals for system operation. The following signals are generated over three wires:
• Rest position.
• Slide open request (press and hold switch - first detent of
open position).
• Automatic slide open request (press further to second
detent and release).
• Tilt open (press and hold).
• Slide close request (press and hold switch - first detent of
close direction).
• Automatic slide close request (press further to second
detent and release).
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Sunroof Motor/Module (SHD): The motor is powered to open, close and lift the sunroof
panel. The motor contains two hall effect sensors that monitor the motor shaft rotation pro-
viding sunroof panel position.
The hall sensors also provide the end limit cut
out function for the SHD once the system is ini-
tialized. The SHD counts the pulses and cuts
the motor out prior to the detected end run of
the sunroof panel.
The combined motor module has a pin con-
nector for interfacing the switch, and vehicle
harness (power, ground and Bus.)
The electronic controls and relays are contained in the sunroof module (PM-SHD). The
module is connected to the P-Bus (E38 >99 MY on the K-Bus) for comfort closing/open-
ing and diagnosis/fault memory purposes.
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System Components: Inputs - Processing - Outputs
/K-BUS