Electronic immobilizer

The electronic immobilizer is an anti-theft and start-enabling device.

The CAS control unit controls the electronic immobilizer.

Each remote control unit has a transponder chip. The ignition lock is surrounded by a ring antenna.

Power is supplied from the CAS control unit to the transponder chip via this coil (remote control key does not require a battery).

The power supply and data transfer function is performed according to the transformer principle. For this, the remote control sends identification data to the CAS control unit.

If the identification data are correct, the CAS control unit activates the starter via a relay which is located in the control unit.

At the same time, the CAS control unit sends the DME control unit an encoded release signal (alternating code) to start the engine. The DME control unit only enables the start if a correct release signal has been received from the CAS control unit.

These operations may result in a slight delay in starting (up to half a second).

The following faults are stored in the DME control unit:

• Missing or disturbed release signal from the EWS control unit
• Alternating code from the CAS control unit does not tally with the alternating code computed by the DME control unit.

If a fault is detected, the engine start is blocked.