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All window operations signals are digital inputs to the door module and GM III.
• Comfort closing/opening of the windows from the driver’s  lock cylinder. The remote key
provides opening only.
• When the ignition key is in accessory or “on” position press the switch to open or close
the  windows.  Window  operation  is  possible  with  the  ignition  switched  off  until  a  front
door is opened or 16 minutes (maximum) has elapsed.
• Window load switching is through relays. The front window control relays are located in
the door modules, the rear window relays are in the GM III. The GM III monitors the cur-
rent draw for end limit position. The maximum run time for the window motors is limit-
ed to 6 seconds in the one-touch mode. This allows the motors to be switched off if the
end limit load sensing fails.
E53 Style Window Switches:The E53 power window switch design is a push - pull type
switch. Each switch provides the GM with the coded ground signaling strategy as previous
two wire switches.
Pushing a switch to the first detent and holding
provides
a  single  ground  signal  on  one  wire
requesting  the  GM  to  operate  the  window
motor in the down direction. 
When  released,  the  ground  signal  is  removed
and the window motor stops.
Momentarily pushing the switch to the second
detent and releasing provides
an  additional
ground  signal  on  the  second  wire  requesting
the  “one  touch  mode”,  operating  the  window
motor automatically. 
The motor runs the window down until it reach-
es the end stop.  
The  switch  functions  in  the  same  manner  for
the  upward  run  of  the  window  motor  but  the
ground signal sequencing is reversed.
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Central Body Electronics ZKE III
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Power  Window  Motors: The  window  motors  are  mounted  on  the  cable  regulators.  The
window  motor  control  circuit  consists  of  two  wires  for  operating  the  motor  in  both  direc-
tions. 
The  motors  are  activated  by  relays  in  the  GM  of  door
modules  (front  doors).  The  relays  provide  either  power
or ground depending on the direction of window travel.  
The  GM  controls  the  polarity  of  the  motor  based  on  a
request  to  run  the  window  (window  switch,
Convenience Opening/ Closing). 
The windows are run to the limit stops which is detect-
ed  by  an  amperage  increase  in  the  control  circuit.
Additionally,  the  window  run  cycle  is  limited  to  a  6-8
second duration if in case the amperage increase is not
detected or there is a malfunction with the regulator. 
Window Motor Limit Stop Function: If the windows are run up and down continuously
a limit stop function is activated to prevent the window motors from overheating. The GM
monitors the number of times the window motors are activated. Each cycle is counted and
stored in memory.  
If the repetitive window activation (up/down) exceeds one minute, the GM deactivates the
internal relays and disregards any further input requests. The GM provides motor activation
after  a  short  duration  but  not  for  the  full  one  minute  monitoring  cycle.  Over  time,  the  GM
slowly reverses the stored count of activation until the stored number equals 0.
Convenience  Opening/Closing: The  GM  provides  the  convenience  open/close  feature
providing control of the power windows (and sunroof) from outside the vehicle with the key
in the driver’s door lock cylinder. The FZV provides the same function for the opening only.
• The anti-trap feature is active during convenience closing from the driver’s door lock.
• The convenience open feature provides outside activation of the windows and sunroof
in the same manner.
• If the GM receives a request to operate convenience close or open for more than 110
seconds, the function is deactivated and a fault code is stored.
• The  Car  Memory  Feature  can  activate  and  deactivate  the  Convenience  Open  Feature
from the FZV’s control.
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Central Body Electronics ZKE III
FRONT DOOR
REGULATOR
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        Page 48 of 80
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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Central Body Electronics ZKE III
System Components:   Inputs - Processing - Outputs
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        Page 50 of 80
Workshop Hints
SHD Self Diagnosis
The  SHD  monitors  operation  and  stores  fault  codes  if  a  defect  is  determined.  The  SHD
monitors the following conditions:
• SHD motor relays:The relays are checked for sticking contacts (plausibility) and non
functional contacts.
• Hall  effect  position  sensors:The  SHD  must  detect  a  pulse  frequency  from  the  hall
effect sensor(s) during operation.
• Sunroof Switch: The SHD monitors the signal plausibility of the coded signaling from
the sunroof switch.
Sunroof Fault Response Characteristics
If a fault occurs with any of these functions, the SHD responds as follows:
•  Overrides the end run detection.
•  Switches the motor off if the relay contacts stick for more than 500 ms.
•  Switches the motor off if pulses are not received.
Emergency Operation of the Sunroof
If the sunroof motor does not respond to the switch signals, the hex key in the trunk lid tool
kit is used to manually turn the motor shaft drive.
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        Page 75 of 80

General Functions of ZKE III
Consumer Cut Off
The Consumer Cut Off function interrupts battery voltage to circuits preventing inadvertent
battery  drain  if  one  of  these  consumers  were  to  remain  activated.  Circuits  controlled  by
consumer cut off will be switched off as the GM enters into the sleep mode.
For example, the interior lights are connected to the consumer cut out circuit (KL 30) and
can  remain  on  if  one  of  the  control  switches  are  left  on.  The  consumer  cut  off  will  deacti-
vate KL 30 to the interior lighting after 16 minutes (or with the DISplus/MoDIC).
The  following  circuits  are  con-
trolled by consumer cut off:
• Map/Reading Lights
• Glove Box/Luggage Compart- 
ment Lights
• Transmission Range Indicator  
Light
• Overload Protection Relay for
- Power Seat Motors
- Steering Column Motors
Overload Protection
The seat and steering column motors receive
operating  power  through  the  consumer  cutoff/
overload protection relay module. The consumer
cutoff  signal  from  the  GM  signals  the  relay  to
maintain operating power to the consumers. 
If the relay module detects an increase in amper-
age (overload) the relay will open. The relay mod-
ule  (K-72)  is  located  in  the  electrical  carrier
behind  the  glove  box.  The  relay  is  reset  by
switching  the  ignition  “off”  for  16  minutes,  dis-
connecting the relay or the DISplus/ MoDIC. 
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Central Body Electronics ZKE III
E38 Shown
Overload
Protection Relay
Module