1995 BMW 740il wipers

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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Central Body Electronics ZKE III
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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
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.