Wiper BMW 740IL 1994 E38 Central Body Electronics ZKE Manual

Table of Contents
SubjectPage
Central Body Electronics (ZKE III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Objectives of the Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Purpose of the System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
System Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Power Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Windshield Wiping/Washing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Headlight Washing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Rear Window Wiper/Washer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Rain Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Central Locking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Trunklid/Tailgate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Remote (Keyless) Entry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Car Memory/Key Memory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Anti-Theft (DWA) System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Power Windows/Sunroof . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Interior Lighting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Visual Entry Aid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Seat/Mirror/Steering Column Memory. . . . . . . . . . . . . . . . . . . . . . . . . . 58
Seat Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Steering Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
General Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75
Consumer Cut Off/Overload Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Sleep Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Review Questions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Windshield Wiping/Washing
Purpose of the System
The windshield wiping/washing functions are controlled by the GM III when the ignition is
in position KL R or KL15. The system has four wiping stages and four interval wiping
speeds. The wiper motor output control is through two relays (double relay >98 MY, except
E38) that are located in the Electonics box (E box).
The Windshield Wiping System can also be supplemented with the Rain Sensor system as
optional equipment. The Rain Sensor detects rain drops on the windshield and automati-
cally activates the wipers when the stalk switch is in the intermittent position.
System Components
Wiper Stalk Switch Input:The wiping stage inputs are coded signals through a two wire
link with a combination of high/low inputs. The wiping stages include:
Single (S): Momentarily holding the wiper
switch down in the single position provides a
momentary ground signal to activate a single
sweep in slow speed.
Slow (I) and Fast (II): The stage I and stage II
wiping speeds are road speed dependent.
Stage I switches to intermittent when the vehi-
cle is stopped and stage II switches to stage I
when stopped.
Windshield Washing: The wash request provides a switched ground input to the GM by
pulling the stalk rearward. The GM activates the windshield washer pump directly.
Intermittent (Int): The intermittent wiping time inputs are provided by a potentiometer
mounted in the wiper stalk switch (1 through 4). The intermittent wiping intervals are also
dependent on the road speed. As road speed increases, the wiping interval is shortened.
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Rear Window Wiper/Washer System (E39 Sport Wagon and E53): The system is
included in the scope of ZKE however is not controlled directly by the GM. The control elec-
tronics are integrated into the rear wiper motor assembly. The control electronics contains
two hall sensors, one for monitoring park position and other for the end stop, or to signal
reverse direction of the wiper motor. The control electronics are connected to the vehicle
electrical system via a single seven pin connector.
The rear wiper system is operator controlled
through the wiper stalk switch providing the fol-
lowing functions:
• Intermittent rear window wiping
• Programmed rear window wiping interval
• Operation of the rear window washer
Pressing the wiper stalk forward to the first detent activates the rear wiper in the intermit-
tent mode
. The timed interval is approximately 7-12 seconds. The full sweep and park posi-
tions are recognized by the two hall sensors on the motor gear assembly. If the wiper is
switched OFF, the wiper blade will return to the park position.
The programmed wiper interval procedure is as follows:
• Briefly switch the rear wiper ON/OFF
• Wait the desired interval time
• Switch the rear wiper ON again
• The OFF time will be the programmed interval - up to approx. 30 seconds
Rear window washing is activated by pressing the wiper stalk switch to the full forward
position.
The washer pump operates followed by two full wiping cycles. The wipers will then
switch to the intermittent wiping mode. Additionally, the system automatically controls the
following safety and convenience features:
• Wiper interrupt with the rear glass opened
• Wiping interrupt with a blocked wiper arm
• Continuous wiping when the vehicle is shifted into reverse
When the transmission is shifted into reverse, the wiper will switch to continuous operation
until the vehicle is shifted out of reverse. This signal (high) is provided by the LCM III when
it activates the back up lights.
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Central Body Electronics ZKE III
Rain Sensor (AIC - if equipped)
Purpose of the System
The Windshield Wiping System is also available with an optionally equipped Rain Sensor.
The Rain Sensor provides added driver convenience and enhances safety by automatical-
ly activating the intermittent function of the windshield wipers when water droplets are
detected on the windshield.
System Components
Rain Sensor: The unit is mounted on the top center area of the interior windshield surface
directly behind the rear view mirror. The unit contains:
• Optical Prism Body:This portion of the unit is per-
manently fixed to the windshield. It can not be
removed and can only be replaced with a replacement
windshield.
The prism body has a reflective surface that faces the
back of the windshield. The prism body also acts as
the windshield mount for the Rain Sensor Control
Module.
• Rain Sensor Control Module:The control module incorporates the following;
- Infra Red Emitter and Detector Diodes
- Optics heater (prevents condensation from forming on diodes and prism)
- Optics evaluation and control electronics
- Photo cell to detect night driving
The control module requires four signals for operation; KLR, KL31, Windshield Wiper Motor
Park Signal Feedback and K-Bus interface.
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Central Body Electronics ZKE III
Principle of Operation
The optical infra red portion of the sensor operates by the principle of refraction (bending
of a light ray). The rain sensor control module activates the emitter diode which sends a
beam of infra red light through the windshield on an angle. The set angle is important
because it provides the beam with a calculated reflective path back to the detector diode.
The beam is reflected back into the windshield due to the density difference of the glass
compared with the ambient air on the outside surface of the glass. When the windshield is
clean (no rain drops, moisture or dirt) the detector diode receives 100% of the infra red light
that the was sent by the emitter. With this condition, the rain sensor evaluation electronics
determines the windshield is free of rain drops.
The density of water is closer to that of glass than air. When rain starts to accumulate in
the sensor monitoring area, it causes part of the infra red beam to extend past the outside
surface of the glass and into the rain drop. When this occurs, the beam is refracted and
only part of the beam returns to the detector diode.
The rain sensor evaluation elec-
tronics determines the windshield
has a few rain drops (or dirt) on it.
The intensity of the returned infra red beam diminishes proportionally with an increase of
water droplets. The rain sensor control module generates a signal proportionate to the
amount of rain on the windshield and broadcasts it to the GM via the K bus.
The GM activates the intermittent wipe cycle if the windshield wiper stalk switch is in the
intermittent position. It also adjusts the frequency of wiping the windshield depending on
the four position thumb wheel.
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Central Body Electronics ZKE III
Rain Sensor Function
The rain sensor is online as soon as it receives KLR operating power.
• When the windshield wiper stalk switch is placed in the intermittent position the GM sig-
nals the rain sensor control module via the K-Bus of the request for intermittent wiping
and the position of the knurled wheel (sensitivity).
• As an acknowledgement, the rain sensor sends a command via the K Bus to activate the
wiper motor. If more than 12 seconds pass before the GM receives the acknowledge-
ment, the GM concludes the rain sensor has a defect and operates the intermittent wipe
function as a system not equipped with a rain sensor. The wiper intermittent cycling is
based solely on the knurled wheel setting.
• The rain sensor continuously monitors the windshield for rain accumulation and signals
the GM to activate the wipers based on the knurled wheel position and how fast the rain
accumulates on the windshield.
• The knurled wheel position signal (1-4) via the K bus informs the rain sensor of the select-
ed level of sensitivity.
- Position 1 (least sensitive) delays the wiper activation signal.
- Position 4 (most sensitive) sends the wiper activation signal to the GM sooner.
• When the wiper motor park contacts signal the GM of the wiper arm position, the signal
is simultaneously sent to the rain sensor as an indication that the windshield has been
cleared of water drops and causes the rain sensor to reset the sensitivity delay timer back
to 0.
• If night time driving is detected via the integral photocell, the sensitivity to water droplets
is increased causeing a shorter delay than day time driving.
• Depending on the intensity of the rain the wipers will be operated continuously as if set in
the normal wiper stalk switch position regardless of the knurled wheel setting. For this
reason, the vehicle speed signal on the K bus is not utilized on rain sensor equipped wiper
systems.

• If the ignition switch is turned off with the wiper switch in the intermittent position, the rain
sensor will only become active after the ignition is switched back on and one of the fol-
lowing occurs:
- The stalk switch is moved from the intermittent position and then back.
- The knurled wheel setting is adjusted.
- or the wash function is activated.
The reasoning behind this switching strategy is to have the driver make a conscious deci-
sion to activate the system themselves.
Rain Sensor Control Module Adaptation
The rain sensor control module adapts to the optics system environment as follows:
Windshield Aging:As the vehicle ages the possibility of stone chipping in the rain sensors
monitoring area may occur which will cause a loss of light in the optics system.
The control module adapts for loss of light based on the intensity of the detected infra red
light with a cleared windshield (wiper motor park signal). Therefore, the rain sensors func-
tion is not adversely affected due to windshield aging.
Dirty Windows:The rain sensor adaptation reacts less sensitively to a dirty windshield
(dirt, road salt, wax residue) after a completed wipe cycle. A dirty windshield has a film on
it that diminishes the ability of the infra red to refract into present water droplets. This caus-
es a delay in the rain sensor detection capabilities which lengthens the time intervals on an
intermittent wipe.
Windshield Wiper System Failsafe Operation
The GM provides failsafe operation of the wiper system if faults are detected with any of the
following input signals:
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Central Body Electronics ZKE III
Function Faulted Input Detected Failsafe Function
Intermittent Wipe
Short or open circuit of
the knurled wheel signalDelay value for
setting 3 used.
Intermittent wipe
with Rain SensorFaulted Rain Sensor or
K-Bus Signal corruptNormal Intermittent
wipe implemented
Wiper Motor not
Functional MovingPark contact feedback
signal takes longer than
16 secondsWiper motor control
deactivated for 3
minutes

Workshop Hints
Windshield Wiper Blade Service
To access the wiper blades for cleaning or replacement,the following is required:
• With the ignition switched on (KL15), switch the wiper stalk to the “Intermittant” wipe
mode.
• Switch the ignition off when the wiper arms are in the “upright” position.
CAUTION: Do not allow the wiper arm to spring back against the windshield, glass
breakage will occur!
Rain Sensor Equipped Vehicles
Make sure the wiper blades are in perfect condition. Only use window cleaner to clean the
windows. Dirty windows can cause the Rain Sensor control module to set a fault
due to the end limits of its adaptation abilities.
Rear Window/Wiper
The wiper arm and driveshaft are connected by
splines.
Special tool #61 1 320 is required to hold the drive
shaft in the park position prior to installing the wiper
arm on to the drive shaft.
Windshield Wiper System Diagnosis
The GM monitors the following circuits:
• Wiper Potentiometer • Wiper Motor • Terminal 30
• Double Relay • Windshield Washer Pump
Note: The wiper/washer operation will be interrupted during engine cranking. The GM pro-
vides this “unload” feature to preserve the battery voltage for the starter motor.
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Door Contact Hall Sensor: Also included in the drivers door actuator is a third hall effect
sensor. This sensor signals the door open/closed status to the GM. This sensor replaces
the door jamb mechanical switch of previous systems. The rotary latch plate position acti-
vates the door contact hall sensor.
• When the door latch is closed, current flow
through the sensor is <5 mA (0).
• When the door is open, current flow through
the sensor is >12 mA (1).
The passenger side front door and both rear
door lock actuators only include this hall effect
sensor (hall sensor 3). Hall sensors 1 & 2 are
not required.
Trunk Lid Close (E38 SCA)/Tailgate and Window Latching System (E39/E53): The
tailgate/trunk lid is opened by any of the three input signals: FZV, remote button and unlock
switch pad (push - trunk lock cylinder E38).
These inputs request the rear latch
actuator control circuit to be
switched to ground (exception:
presence of road speed signal,
key on with FZV request.)
The rear latch actuator unlatches
the mechanism and signals the
GM of the open latch status. The
SCA motor rotates the striker
180
O. Feed-back signalling stops
the motor. E38 - When closing the
trunk lid the trunk latch micro-
switch signals the GM to activate
the SCA motor to pull the lid
down.
Rear window unlatching is requested by the rear window switch ground signal. This signal
initiates activation of the rear window actuator relay control circuit which activates the rear
window actuator. The actuator unlatches the mechanism opening the window. The latch
simultaneously provides an open window signal for the rear window wiper motor module
as well as an interior light on request (via the wiper module).
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Shown
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Review Questions
1. List the functions directly controlled by the GM III._______________________________
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2. How does the GM III communicate with other control modules?__________________
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3. What effect does road speed have on the wiper system? What effect does it have on
an AIC equipped vehicle? Where does the road speed come from?_______________
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4. How does the GM III recognize the key position from the drivers door?____________
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5. Describe the procedure used by the GM III to recognize an FZV key. Can the GM
differentiate between different keys? How many can it recognize?________________
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6. What “convenience” features are available from the FZV key?____________________
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7. Describe what happens when the GM receives the crash signal from the MRS.
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8. Why does the SHD (sunroof) module require initialization but the windows do not?
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