10
EWS
Ring Antenna
The Ring Antenna is an inductive coil installed around the lock cylinder which provides
power for the transponder in the key and the communication link (antenna) between the key
and the transmit/receive module.
Transmitter/Receiver Module
The Transmitter/Receiver module supplies power to the transponder through the ring
antenna and controls the flow of data between the transponder and the EWS II control
module.
Data transmission between the transmitter/receiver module and the transponder takes
place over a radio frequency of 125 KHz amplitude modulated AM signal.
The transmitter/receiver module converts the
analog data received through the AM signal to
digital data and transfers it to the EWS II control
module over a single wire bi-directional data
interface.
8510109
8510110
Workshop Hint:
On E34 and E36 models the transmitter/receiver mod-
ule is located under the dash near the steering column.
On E 31, E38 and E39 models the transmitter/receiver
module is located in the steering column cover on the
right hand side of the column.
Inductive
coil
Ring Antenna
Transmitter
Receiver
Module
Transmitter/Receiver Module under Dash
Connector
to EWS II
Module
Ring Antenna
fits around the
Lock Cylinder
