1998 BMW 525i key battery

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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System Components
Remote Key: Features:
• 3 volt lithium battery (commercially available CR 2016)
is used as the power supply for the key transmitters.
• An EEPROM is used to store the key data.
The data is not lost when the battery is re-
placed and initialization is not required.
• The key incorporates an LED that signals the opera-
tor of signal transmitting, key initialization status and
key self test indication.
• The keys are delivered
with a four color label
sheet containing differ-
ent colored labels for
each of the four pos-
sible FZV keys.
This is helpful to differenti-
ate the FZV keys during initialization preventing the pos
sibility of mis-assigning the key ID which would change
the encoded Key Memory functions.
Model Year 2000 Key
Visual Changes:
• New appearance with blue and white BMW roundel.
• New button arrangement (larger buttons) with seq-
uential operation (enhanced operating convenience).
Functions the same as the previous key.
• Rechargeable battery replaces replaceable batteries.
Charged by EWS ring antenna.
• The key housing is encapsulated and can not be
opened.
• The LED has been omitted.
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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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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 “