charging BMW 540I 2000 E39 Central Body Electronics ZKE Manual

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).
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Central Body Electronics ZKE III

The key data is stored in a transponder chip. The transponder chip is a wireless read and
write EEPROM. It is powered via the ring coil at the steering lock. Power is applied elec-
tromagnetically when the key is in the ignition switch from KL R.
The power supply is used both for data transfer as well as for charging the battery. This has
been made possible by new development of the transponder chip.
As with previous systems, every press of an FZV key also provides the battery charge con-
dition. When the FZV electronics receives a low power condition message three successive
times, the GM sets a fault indicating a low battery within a specific key. The LCM is also
informed via the bus system and alerts the driver via an instrument cluster matrix message.
If the battery is recharged (used operate car), the fault will be automatically deleted when
five successive messages are received indicating a charged battery condition.
The battery has no affect on the EWS III communication function!
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Central Body Electronics ZKE III