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WINDSHIELD WIPING/WASHING
• The GM III controls all of the windshield wiping/washer and headlight washing functions.
• Output  control  of  the  wiper  motor  is
through  the    windshield  wiper  double
contact  relay.    The  relay  is  located  in  the
engine  compartment  E-box  and  is  tan  in
color.
• The system continues to have four wiping
stages  and  four  interval  wiping  speeds.
The wiping stage inputs are coded signals
through a two wire link with a combination
of  high/low  inputs  as  on  previous
systems. 
• 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
automatically activates the wipers when the stalk switch is in the intermittent position.
Wiper Stalk Switch:
SINGLE: Holding the wiper switch down in the single position provides a ground signal to
activate the slow speed circuit providing wiper operation until the switch is released.
INTERMITTENT: The  intermittent  wiping  time  inputs  are  provided  by  a  potentiometer
mounted in the wiper stalk switch. 
• The intermittent
wiping intervals are
dependent on the
road speed.  
• As road speed
increases, the
wiping interval
delay is decreased. 
SLOW (I) AND FAST (II): The stage I and stage II wiping speeds are also affected by road
speed.  The factory encoded settings are the same as previous systems:
• Stage I automatically switches to intermittent when the vehicle is stopped 
• Stage II switches to stage I when stopped.
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WINDSHIELD WIPER
DOUBLE RELAY  
         
        
        
     
        
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OPTIONAL RAIN SENSOR (AIC)
The  Windshield  Wiping  System  will  also  be  available  with  an  optionally  equipped  Rain
Sensor.    The  Rain  Sensor  provides  added  driver  convenience  and  enhances  safety  by
automatically  activating  the  intermittent  function  of  the  windshield  wipers  when  water
droplets are detected on the windshield.
COMPONENTS:
The  rain  sensor  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
permanently  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 time driving 
The control module requires four signals for operation; KL R, KL 31, Windshield Wiper
Motor Park Signal Feedback and K Bus interface.
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GM III  
         
        
        
     
        
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RAIN SENSOR FUNCTION:
The rain sensor is online as soon as it receives KL R operating power. 
• When  the  windshield  wiper  stalk  switch  is  placed  in  the  intermittent  position  the  GM
signals  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
acknowledgement,  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
selected 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 causing 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
following 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
decision to activate the system themselves.