
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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Central Body Electronics ZKE III 

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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Central Body Electronics ZKE III 

Passenger’s Seat (without memory)
Principle of Operation
The passenger seat control switch is purely a mechanical switching module that activates
the passenger seat motors without position monitoring capabilities. Due to the limited op- 
eration requirements, the passenger seat control switch is not equipped with on board
diagnostics.
The  Passenger  Seat  control  switch  is  equipped  with  an  overload  protection  function.  If
excessive amperage is drawn due to a defective motor or  a switch is stuck driving  a motor
to the end limit, the function activates opening the motor control circuit.
Passenger Seat Motors: Each motor is individually controlled by the Seat Control Switch.  
Each position motor is connected to the seat position switch by a two wire circuit provid-
ing motor activation in both directions (no position recognition).
Passenger Seat Adjustment: Operation of the passenger seat is always possible regard-
less of the ignition key position. Moving a position switch operates a the motor control con-
tacts  directly,  the  switch  applies  voltage  and  ground  path  directly  to  operate  the  motor.
Reversing  the  switch  simply  changes  the  motor  polarity.  More  than  one  passenger  seat
motor can be run simultaneously.
Optional Seat Back Lumbar Support
The optional air bladder lumbar support system is similar in all
vehicles  (if  equipped).  Each  seat  contains  the  following  com-
ponents:
• Four position circular rocker switch in the seat base trim in  
the area of the seat switches.
• Electrically controlled air compressor with over pressure cut 
out under each seat.
• Two  solenoid  activated  air  controlling  valve  blocks  (one  per
air bladder). Each valve block includes an inlet and an outlet
valve.  When  energized  they  direct  air  into  the  bladder(s)  to
inflate or relieve trapped air to deflate the bladders.
• Connecting hoses and air bladders in lower seat back.
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Central Body Electronics ZKE III 

Principle of Operation
The  lumbar  support  system  can  be  operated  at  any  time  regardless  of  key  position.  The
four position circular rocker switch provides power switching to operate the system as fol-
lows:
• Position 1: The internal switch contacts provide a power and ground path for both valve
block  inlet  valves  and  the  air  compressor.  Both  bladders  inflate  until  the  switch  is
released.  If  the  switch  is  held  continuously,  an  overpressure  bypass  valve  opens  on  the
compressor preventing damage to the bladders.
• Position 2: Compressor activated, upper bladder inflates, lower bladder deflates.
• Position 3: Compressor activated, lower bladder inflates, upper bladder deflates.
• Position 4: Compressor is not activated. Upper and Lower bladders both deflate.
This function is not stored in memory for recall.
Diagnosis
The seat lumbar support system is  purely electro-pneumatic control system. No electron-
ic diagnostic communication is possible.
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Central Body Electronics ZKE III 

Sleep Mode
To lower the constant battery draw when the vehicle is parked, the complete ZKE system
will  go  into  the  “Sleep  Mode”  16  minutes  after  the  ignition  has  been  switched  off  and  no
further ZKE function is active. 
For example, the approximate E39 (528i) Battery draw is: 
• Ignition switch off = approx 750 mA.
• One minute after = approx. 560 mA.
•  After 16 minutes (sleep mode) = approx. 18 mA.
All modules in the ZKE system will go into the sleep mode. The P-Bus remains active, how-
ever no data transfer takes place until a wake-up request is received. The general module,
door  modules  or  keyless  remote  module  can  wake  the  system  up  and  put  the  ZKE  back
on line. The K-Bus is active (high) in the sleep mode.
Sleep Mode Criteria:
KL R, KL 15 OFF and no further function activated for 16 minutes.
Wake Up Criteria:
KL R or 15 “ON” or a change in one of the signals listed below.
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Central Body Electronics ZKE III
SIGNAL ACTIVITY ORIGINATING
MODULE
K-BUS High General Module
Door jamb switches (possibility of 4) Low “
Trunk lid lock cylinder microswitch High “
Trunk lid pushbutton microswitch Low “
Interior Trunk lid pushbutton microswitch Low “
Central locking button Low “
Hood microswitch Low “
Trunk Lid microswitch Low “
Interior light switch Low “
FIS sensor Low “
Tilt Alarm sensor Low “
FBZV operational signal High FBZV Module 
Driver’s door lock microswitch      - (lock) High PM-FT/SB
“ “ “ “ - (unlock) High “
Passenger door lock microswitch - (lock) High PM-BT
“ “ “ “ - (unlock) High “ 

Review Questions
1. List the functions directly controlled by the GM III._______________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
2. How does the GM III communicate with other control modules?__________________
_________________________________________________________________________
_________________________________________________________________________
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?_______________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
4. How does the GM III recognize the key position from the drivers door?____________
_________________________________________________________________________
_________________________________________________________________________
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?________________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
6. What “convenience” features are available from the FZV key?____________________
_________________________________________________________________________
_________________________________________________________________________
7. Describe what happens when the GM receives the crash signal from the MRS.
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
8. Why does the SHD (sunroof) module require initialization but the windows do not? 
_________________________________________________________________________
_________________________________________________________________________    
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Central Body Electronics ZKE III 

9. What type of sensor is used to detect the position of a seat with Memory?  What type
of signal does it produce?__________________________________________________
_________________________________________________________________________
10. How does the Seat Module communicate a request for a stored memory position with
the mirror modules?_______________________________________________________
________________________________________________________________________
11. On an E38 with Servotronic, why is the speed signal provided to the GM from both  
the IKE “A” signal and the K-Bus?___________________________________________
________________________________________________________________________
________________________________________________________________________
12. An E38 customer complains that when exiting the vehicle the steering wheel moves 
up. What is the cause of this?______________________________________________
________________________________________________________________________
13. How does the SZM monitor the Seat Heating temperature?_____________________
________________________________________________________________________
________________________________________________________________________
14. What circuits are controlled by Consumer Cut Off? ____________________________
________________________________________________________________________
________________________________________________________________________
15. If a technician double locked a 2000 MY E39 while still inside the vehicle, how could  
he/she exit the vehicle?____________________________________________________
________________________________________________________________________
________________________________________________________________________
16. How is the MY 2000 key charged?__________________________________________
________________________________________________________________________
________________________________________________________________________
17. How is the DWA Disarmed (emergency)?_____________________________________
________________________________________________________________________
18. What functions will deactivate the exterior door handle lighting? _________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________     
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Central Body Electronics ZKE III