
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
12520101.eps 

Workshop Hints
Windshield Wiper Blade Service
To access the wiper blades for cleaning or replacement,the following is required:
• With the ignition switched on (KL15), switch the wiper stalk to the “Intermittant” wipe 
mode.
• Switch the ignition off when the wiper arms are in the “upright” position.
CAUTION: Do not allow the wiper arm to spring back against the windshield, glass
breakage will occur!
Rain Sensor Equipped Vehicles
Make sure the wiper blades are in perfect condition. Only use window cleaner to clean the
windows. Dirty  windows  can  cause  the  Rain  Sensor  control  module  to  set  a  fault
due to the end limits of its adaptation abilities.  
Rear Window/Wiper
The  wiper  arm  and  driveshaft  are  connected  by
splines. 
Special  tool  #61  1  320  is  required  to  hold  the  drive
shaft  in  the  park  position  prior  to  installing  the  wiper
arm on to the drive shaft. 
Windshield Wiper System Diagnosis
The GM monitors the following circuits:
• Wiper Potentiometer        • Wiper Motor                           • Terminal 30 
• Double Relay                  • Windshield Washer Pump   
Note: The wiper/washer operation will be interrupted during engine cranking. The GM pro-
vides this “unload” feature to preserve the battery voltage for the starter motor. 
16
Central Body Electronics ZKE III
12510117.jpg 

LED Status (Keys equipped with LED):
The following functions can be checked with the LED:
• Flashing  LED  when  pressing  a  button.
Indicates  that  the  data  is  being  transmitted.
(battery voltage between  3.2 - 2.6 volts)
• No LED activity when pressing a button:
1. ZKE  responds  to  pressed  button  only  to
unlock  a  locked  vehicle.  Indicates  the  bat-
tery is between 2.6 - 2.2 volts.  Replace bat-
tery.
2. No  unlock  of  vehicle.  Indicates  battery  is
below 2.2 volts. Replace battery.
FZV Key Test: Pressing the trunk release and lock buttons together activates the key test. If
the battery and FZV key EEPROM are  “OK”, the LED will come ON for approximately 1 sec-
ond.
FZV Key Rechargeable Battery
From KL R, the battery inside the key head is charged inductively by the EWS ring antenna
via a coil antenna integrated in the key. The charging process is controlled by electronic
circuitry integrated in the key.
• The service life of a radio-control key used under normal conditions corresponds to the veh- 
icle lifespan.
• If the FZV keys are not used (ie: stored in a drawer), the battery will be discharged after
approx. 1.5 years.
• The time required to fully charge a discharged battery is approx. 30 hours.
• The remote control can be operated about 15 times after a charging period of approx. 30  
minutes (driving time).
31
Central Body Electronics ZKE III 

Principle of Operation
DWA Arming/Disarming
• The DWA is armed every time the vehicle is locked from the outside with the door lock
cylinder or FZV key. 
• The  DWA  LED  flashes  as  an  acknowledgment  along  with  the  exterior  lights  and  a
momentary chirp from the siren.
• The GM monitors all required input signals for closed status (door closed, luggage com-
partment  closed,  etc.)  The  inputs  must  be  in  a  closed  status  for  a  minimum  of  3  sec-
onds  for  the  GM  to  include  them  as  an  activation  component.  If  after  3  seconds  any
input signal not in the closed status is excluded (this is acknowledged by the DWA LED)
preventing false alarm activations. The hood switch can be “lifted” to the service posi-
tion to test the alarm with the hood open.
• If the DWA is armed a second time within 10 seconds, the tilt sensor and interior pro-
tection  sensor  are  excluded  as  alarm  activation  components.  This  function  is  useful  if
the vehicle is transported on a train or flat bed truck to prevent false alarm activations.
• While armed, the trunk can be opened with out the alarm being triggered as follows:
- If opened with the trunk remote button via the FZV, the GM prevents the alarm from
activating. (This feature is customizable under the Car Memory function).
- If  opened  with  the  key  at  the  trunk  lock  cylinder  the  trunk  key  position  switch  sig-
nals the GM and in the same manner prevents the alarm from activating.
In either case, when the trunk is returned to the closed position, it is no longer con-
sidered as an activation signal. 
Panic Mode Operation: When the trunk button is pressed and held, the GM is signaled
to activate the siren for the Panic Mode. The panic mode is function with either an armed
or disarmed DWA system.
Emergency Disarming: Emergency disarming occurs automatically if a key is used to turn
the ignition switch on and the EWS accepts it. The EWS signals the GM to unlock the doors
and deactivate the DWA.
40
Central Body Electronics ZKE III 

Rear Window Roller Sunblind Operation
The roller sunblind is activated by momentarily pressing and releasing (one touch) the sun-
blind rocker switch in the SZM. The SZM activates the motor in the appropriate direction.
The SZM switches the motor off when the motor amperage increases indicating the blind
has reached the end of its intended travel.
Fault Monitoring: The SZM continually monitors the motor drive amperage loads to deter-
mine jamming or blockages. If current values exceed preset values, the motor is switched
off immediately.
Faults are stored in the SZM for opens or shorts in the motor or motor’s wiring circuit. The
SZM also provides diagnostic requests to monitor the switch input status via the DISplus/
MoDiC.
69
Central Body Electronics ZKE III
KL 31 (GROUND)KL 31 (GROUND)
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KL 30 (BATTERY)KL 30 (BATTERY)-+
KL 15 (IGNITION ON)KL 15 (IGNITION ON)
KLR (ACC)KLR (ACC)
KL 87 (OPERATING POWER)KL 87 (OPERATING POWER)
58G (PANEL LIGHTING)58G (PANEL LIGHTING)
LCM IIILCM III
PDC
EDC
DSC
MREAR WINDOW
ROLLER
BLINDSREAR WINDOW
ROLLER
BLINDS
DRIVER’S SEAT HEATINGDRIVER’S SEAT HEATING
PASSENGER’S SEAT HEATINGPASSENGER’S SEAT HEATING
K BUSK BUS
PDC CONTROL
MODULEPDC CONTROL
MODULE
EDC CONTROL
MODULEEDC CONTROL
MODULE
SZMSZM
DSC III
CONTROL
MODULEDSC III
CONTROL
MODULE
ACTIVE SEAT
CONTROL
MODULESACTIVE SEAT
CONTROL
MODULES
System Components:   Inputs - Processing - Outputs