ID transmitter

The ID transmitter evaluates the signals from the aerials. It also sends high-frequency radio signals to the remote control receiver (868 MHz/315 MHz, country-specific). Inserting the ID transmitter into the fixture deactivates all Comfort Access functions.

Fig 1: Identifying Mechanical Key And ID Transmitter

Courtesy of BMW OF NORTH AMERICA, INC.

Item	Explanation
1	ID transmitter
2	Mechanical key

As opposed to the remote key, the ID transmitter on optional equipment 322 "Comfort Access" has a battery. The battery is needed for the following reasons:

Recharging must not be needed, increasing convenience (e.g. by inserting in the fixture or from external charging station).
The ID transmitter consumes more power than the remote key.
The ID transmitter battery has a significantly higher capacity with a longer life.

An integrated mechanical key is provided to open or close the vehicle manually in an emergency (e.g. flat battery or local radio interference).