
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 

3
Central Body Electronics ZKE III
Central Body Electronics (ZKE III)
Purpose of the System
The Central Body Electronics (ZKE III) system manages the following functions:
GM III
• Windshield Wiping/Washing
• Windsheild Rain Sensor (AIC)
• Headlight Washing
• Tailgate Wiping/Washing
• Interior Lighting
• Central Locking
• Keyless Entry
• Key Memory
• Power Trunk Release
• Electric Opening of Tailgate
• DWA Alarm System
• Servotronics
• Consumer Cut-off/sleep mode
• DiagnosisDriver’s Door Switch Block/
Module
• Power Windows
• Mirror Adjustment/Memory/   
HeatingPassenger’s Door Module
• Mirror Adjustment/Memory/
Heating
• Power Windows
Sunroof Module
• Power SunroofSeat/Mirror/ Steering Column
Memory Module
• Seat Adjustment/Memory
• SteeringColumn Adjustment/
Memory
The ZKE III system was introduced on the E38 and is used in the E39 and E53. Most of the
functions  operate  the  same  on  these  vehicles  with  minor  changes  and  added  features  to
the system.
ZKE III  represents  the  combination  of  Body  Electronics  functions  into  one  central  control
module, the General Module (GM).  

4
Central Body Electronics ZKE III
System Components
General  Module  (GM): The  GM  is  reponsible
for  the  operation  and  central  coordination  of
body  electronics.  The  GM  is  a  micro-computer
that  is  the  central  component  (heart)  of  the
Central Body  Electronics. The GM is located be-
hind the glove box. 
The main objectives for using the GM are:  
The  GM  requires inputcommands  to  perform
Central  Body  Electronics  functions.  The  inputs
are  supplied  by  digital  switched  signals  such
as:
• Trunk Lock Microswitch - supplies voltage (KL  
30) to the GM when switched. A path to gro-  
und is provided by the GM (internally). The 
GM monitors the switched input voltage. 
• Central Lock Button - supplies a ground cir-   
cuit to the GM when switched. The GM sup- 
plies and monitors a reference voltage (5v)     
that is “pulled” low when the switched gro-
und path is provided.  
The  GM processesthe  input  information  and
contains “coded” instructions that allow a spe-
cific output control of functions.
The  GM  will  produce outputfunctions  using
internal  transistors  to  switch  current  flow  (pro-
viding  voltage  or  ground)  through  circuits  and
actuators.  Actuators  are  the  final  controlling
devices  used  by  the  GM  to  operate  or  control
various  output  functions  such  as  relays  and
motors.
• Increase Overall Reliability 
• Centralize Electronic Systems
• Decrease Assembly and Service Repairs 
• Centralized Diagnosis of all ZKE Components 
• Individualization of Features (Coding) 
CENTRAL LOCK BUTTONCENTRAL LOCK BUTTON
TRUNK LOCK BUTTONTRUNK LOCK BUTTON
KL 30KL 30
TRUNK LOCK MICROSWITCHTRUNK LOCK MICROSWITCHSignal Monitor
5v
Supply/
Monitor
GM
FUEL 
FILLER
FLAP 
RELAY
Transistors
GM
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7
Central Body Electronics ZKE III
Power Distribution
The power distribution box for the
E38  is  incorporated  in  the  Electr-
onics  box  in  the  engine  compart-
ment. 
The power distribution box for the
E39 and E53 is inside the vehicle. 
The  main  fuse  box  is  located
inside  the  glove  box  above  a
hinged panel. 
A  “pull  out”  fuse  designation  card
is also located in the fusebox. This
notes:
• Fuse value in amps
• Location
• Circuit listing by fuse
The placement of the power distribution box is
close  to  the  main  electronics  carrier behind
the  glove  box.  The  modules/relays  located  in
the electronics carrier include (examples):
• General Module III (GM III)
• Drive away protection (EWS II)
• Anti-lock Brake (ABS/ASC+T)
• Light Check Module (LCM) - behind right kick
panel
• Overload protection relay module
An  auxiliary  fuse  block  is  located in  the  trunk
above  the  battery.  In  addition  to  fuses,  the
auxiliary fuse block also contains relays (exam-
ples):
• Fuel filler flap lock motor relay
• Fuel pump relay (some vehicles)
• Rear defroster relay
• Unloader relay 
FUSE
DESIGNATION
CARDFUSE BOX DROPS
DOWN AFTER TURNING
TWO THUMB SCREWS
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Fused Power Distribution Centers
The E38, E39 and E53 utilize high amperage fused power distribution centers. 
The  E38  and  E39  locations  are  found  under  the  carpet  on  the  passenger’s  side  floor  and
in the right rear area of the trunk, forward of the battery.
The  X5  utilizes  a  single  high  amperage  fused
power  distribution  center  located  next  to  the
left  side  EHC  air  reservoir  beneath  the  cargo
area floor paneling.
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Central Body Electronics ZKE III
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System Components 
- with the Principle of Operation
Driver’s  Door  Lock: The  lock/unlock  signals
from  the  driver’s  door  lock  cylinder  are  input  to
the  driver’s  door  module  from  the  two  micro
switches  on  the  lock  cylinder.  The  driver’s  door
switchblock module carries out the locking func-
tion of the driver’s door.  
The  windows  and  sunroof  can  be  closed  or
opened  by  holding  the  key  in  the  lock/unlock
position (convenience closing/opening feature). 
The  signal  to  lock  the  remaining  doors  and  fuel  filler  flap  is  passed  over  the  P-Bus  to  the
GM III and passenger’s door module. The locking of the passenger’s door is carried out by
the  passengers  door  module.  The  rear  doors,  luggage  comparment  and  fuel  flap  locking
are carried out directly by the GM III. All four doors will be pulled into the double lock posi-
tion when locking from the driver’s door.
The control of the actuators in the front doors is through final stages in the door modules.
The rear doors, trunk and fuel filler flap actuators are controlled by internal relays in the GM
III. When locked, the GM III will not carry out any opening commands from the central lock-
ing button or luggage comparment interior release button.
Luggage  Compartment  Lock  Cylinder  (except  E53/E39  Sport  Wagon): The  vehicle
can be locked/ unlocked (prior to 2000 MY) from the luggage compartment lock cylinder.
The lock/unlock micro switch inputs are processed in the GM III and the locking commands
are carried out. 
The signal is passed over the P-Bus to the
door  modules  to  lock/unlock  the  front
doors  and  the  GM  III  locks  the  rear  doors
and fuel filler flap. 
All door actuators are placed in the double
lock position. Removing the key in the hor-
izontal position will activate the valet mode
and prevent the valet key from opening the
luggage comparment.
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Central Body Electronics ZKE III
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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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Central Body Electronics ZKE III
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E39 Sport Wagon 
Shown
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Remote (Keyless) Entry FZV
Purpose of the System
The Remote Entry System offers the following:
• Locking/unlocking of doors, luggage compartment (tailgate), fuel filler lid.
• Selective unlocking of driver’s door (same as with key in the lock cylinder).
• Arming/disarming of DWA alarm system.
• Remote unlocking of the trunk (tailgate) only.
• Comfort opening of windows and sunroof.
• Interior lighting activation (search mode).
• Panic mode alarm activation.
• Changing code signals - coded signals from transmitter change with every operation.
• Automatic correction for up to 1000 erroneous activation signals.
• Transmitter initialization procedure - including up to four key operation and Key Memory.
• Replacement batteries.
• Low transmitter battery in vehicles equipped with Check Control. 
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Central Body Electronics ZKE III
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