overheating BMW M5 2000 E39 Central Body Electronics ZKE Manual

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
615200114.eps

68
Central Body Electronics ZKE III
Center Console Switch Center (SZM): From 1999 MY E38, E39 and E53 vehicles are
equipped with a SZM to control the front seat heating and provide a diagnostic interface
with the DISplus/MoDiC via the K BUS.
The SZM directly controls:
• Front Seat Heating
• Rear Window Roller Blind
SZM also provides a unitized switching center
for:
• Park Distance Control (PDC)
• Dynamic Stability Control (DSC III)
• Electronic Damper Control (EDC).
The switch signal output for these systems is a direct output signal. All diagnosis functions
are carried out through their respective control systems.
SZM Monitoring of Seat Heating
Battery Voltage:The SZM switches current supply to the heating elements off when bat-
tery voltage drops below 11.4 volts. However, the heating stage LEDs remain on.
Regulated output current resumes when battery voltage raises above 12.2 volts for more
than 5 seconds.
SZM Internal Temperature: The power output stages for the seat heating elements gen-
erate a considerable amount of heat when in stage 1 operation. The SZM monitors it’s own
internal temperatures and reduces the heating output when internal temperatures rise to a
temperature of 185
OF or switches it off completely above 203OF. As with battery voltage
monitoring, the heating stage LEDs remain on when these temperatures are exceeded.
Fault Monitoring:The SZM monitors the temperature sensors and heating mats for faults.
Detected faults are stored in the SZM. Fault Symptom Troubleshooting in conjunction with
stored faults will initiate the diagnostic paths using the DISplus/MoDiC. The following faults
can be recognized:
• Shorts or opens in the wiring circuits.
• Shorts or opens in the temperature sensors.
• Open in heating element.
If a short is detected in the temperature sensor, the seat heating is switched off to prevent
overheating. The Stage LEDs are also switched off with this fault present.