Your vehicle's key fob, whether original or a replacement remote key for BMW, is battery powered. In some models, that battery is rechargeable. Like any device powered by a rechargeable battery, it is necessary to periodically charge the battery for optimal operation.
How to recharge the BMW Key Battery
BMW keys are charged while in the ignition. From position 1 (KL R) and 2 (Run) position the key's battery will be charged using inductive charging. If you have a low battery and would like the key charged up without driving the car simply connect an automotive battery charger your car's battery pos/neg jump start terminals in the engine bay, then insert the key into the ignition and turn it to position 1 and leave it overnight. The charger will prevent your car battery from dying while the key gets charged.
It takes 30 minutes of driving time to recharge a dead battery allowing for 15 key presses, and 30 hours of total driving to fully recharge the battery
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 vehicle 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).
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 electromagnetically 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 condition. 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 effect on the EWS III communication function
Model Year 2000 FZV key
- New appearance with blue and white BMW roundel.
- New button arrangement (larger buttons) with a sequential operation (enhanced operating convenience).
- 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.
- Key will be used in the E46, E38 and E39 vehicles.
- Up to 4 radio-control keys can be operated in conjunction with one vehicle.
Features of the keyless entry system
- Locking/unlocking of doors, tailgate, fuel filler lid.
- Selective unlocking of a driver's door (as with key in lock).
- Arming/dis-arming of DWA alarm system (if equipped).
- Remote unlocking of the tailgate only.
- Comfort opening of windows and sunroof.
- Interior lighting activation (search mode).
- Panic mode alarm activation.
- Automatic correction for up to 1000 erroneous activation signals.
- Low transmitter battery fault code storage in the GM.
- An EEPROM is used to store the key data.
- Keys delivered with a four color label sheet containing four different colored labels for each of the four possible FZV keys.
Remote key initialization
The initialization of the FZV keys is required to establish the Lock/Unlock signal synchronization with the GM. The initialization procedure provides the GM with a key identification number and a "rolling code" for each key. If the initialization is not performed, the GM will not respond to the key signals.
Up to 4 remote keys can be initialized. They must be initialized at the same time. Key initialization is only possible with the vehicle unlocked.
- Close all doors and have all keys available.
- Using key number 1, turn the ignition switch to KL R, then switch off within 5 seconds and remove the first key.
- Within 30 seconds of turning the ignition switch to "off", Press and hold the arrow button.
- While holding the arrow button, press and release ("tap*) the roundel button three times within 10 seconds.
- Release both buttons. The GM will immediately lock and unlock the doors signaling a successful initialization.
- If additional keys need to be initialized, repeat steps 3–5 within 30 seconds.
- Switching the ignition to KL R completes the initialization.
SERVICE NOTE: The key memory function of the GM responds to the key identification number of each key. If the keys are not initialized in the same order prior to initialization, the key memory function activated by the keys will not be assigned correctly.
Always initialize the keys in the same order.
This feature provides the added convenience of identifying users of the vehicle whenever a lock or unlocked signal is generated with the individual FZV keys. A maximum of four FZV keys can be used with the Key Memory feature.
Each of the four keys generate a unique key identification signal (key number) that is transmitted simultaneously with the lock/unlock signals to the General Module. Key Memory does not respond to Lock/Unlock requests from the drivers door lock.
Most of the key memory functions require the vehicle be configured using the "KEY MEMORY" function of the DIS or MoDIC. However, there are a few features that store settings automatically without configuration such as IHKA blower speed and temp setting.
The key ID signal alerts the GM V to communicate with select control systems over the K Bus to store (when locked) or reset (when unlocked) certain driver adjustable settings.
There are features that function as both a Car & Key Memory feature.
Example: the Automatic Seat Adjustment feature is encoded as a Car Memory Function with the following possibilities:
- when unlocking,
- when opening a door after unlocking
- or not active at all.
If active, the seat positions are stored and reactivated by the Key Memory function for individual users of the car.
Replacing your BMW key fob
If your battery cannot be recharged, it may be necessary to replace your BMW remote key. Key fobs are available from your local BMW dealer, or through reputable online resellers like Bimmernav and BimmerTech.