Electronic Vehicle Immobilization

Electronic Vehicle Immobilization

Electronic vehicle immobilization
The electronic immobilizer (EWS) is both an anti-theft device and start release.
The 4th generation EWS is an enhancement of the EWS used to date. This enhancement uses a new and modern encryption method.
Each vehicle is assigned a 128-bit secret code. This secret code is stored in a BMW database. This means that the secret code is only known to BMW.

The secret code is programmed and locked in the following control units:
- CAS control unit (not E83)
The EWS is integrated in the CAS control unit.
- EWS control unit (only E83)
The E83 has an EWS control unit, but no CAS control unit.
- DME/DDE control unit

When the secret code is locked in the control units, it can no longer be deleted or changed. This means that each control unit is assigned to a certain vehicle. The control units mutually identify themselves with the secret code and the same algorithm.
In the 4th generation EWS, there is no direct line (EWS data line) between DME/DDE and CAS (not E83).
The CAN data line (PT-CAN and K-CAN) and the K bus (also called CAS bus) are used for data interchange of the EWS signal. The K bus is used when an EWS signal cannot be sent on the CAN data line.
E83: As before, data interchange between the EWS control unit and DME/DDE takes place across the direct EWS data line.







Brief description of components
The following components are described for the EWS:

Remote control with integrated transponder chip
A transponder chip is integrated in every remote control; this can both transmit and receive. The data transfer takes place in the same way as a transformer between the loop aerial in the insertion slot or ignition lock (only E83) and the transponder chip. The remote control sends data to the EWS or CAS control unit and receives data from it.
The authorization of the remote control for each vehicle is also coded in the transponder chip.
The EWS or CAS control unit can manage a maximum of 10 remote controls that match the control unit, i.e. a maximum of 6 remote controls can be obtained as replacements.
The EWS or CAS control unit can identify the individual remote controls. This means it is possible to disable or enable individual remote controls. If faults occur during communication between the EWS or CAS control unit and the individual remote controls, these are stored in the fault code memory - separately for each individual remote control.

Loop aerial
The insertion slot for the remote control or around the ignition lock (only E83) is a ring aerial (coil) to query the transponder chip. The transponder chip and EWS or CAS control unit communicate via the ring aerial.

Electric steering interlock