Freelander System Description and Operation
SECURITY
86-5-16 DESCRIPTION AND OPERATION
Operation
Immobilisation System
The immobilisation system prevents unauthorised starting of the vehicle. The immobilisation ECU is a secure interface
between the ECM which cannot be copied or by-passed.
Immobilisation ECU
The ECU ensures that the vehicle is in a safe condition to start the engine. The ECU prevents starter operation if the
transmission selector lever is not in park or neutral. A feed from the automatic transmission solenoid (C0024) is
connected to pin 3 on the immobilisation ECU. The feed is only present when the selector lever is in either park/
neutral. If the selector lever is moved to any other position the feed to the immobilisation ECU is removed and engine
cranking will be disabled.
When the ignition is switched to position 0 (off) and the key is removed from the switch, the immobilisation ECU
becomes active and prevents unauthorised starter operation. Re-mobilisation is achieved only by insertion of a valid
vehicle key into the ignition switch and turning the switch to position I (AUX).
Ignition Switch Transponder Coil and Key Transponder
The transponder coil is supplied with a modulated electric current from the immobilisation ECU. When the key
transponder is within 2 cm (0.78 in) from the coil, with the ignition switch in the position I (AUX), an energy transfer
from the coil to the transponder takes place, similar to the transformer principle, at a frequency of 125 kHz. The ECU
de-modulates and decodes the received data and compares this with identification code data from the ECM. If the
data is correct the ECU allows starter operation.
When the key is inserted in the ignition switch, communications between the transponder and the immobilisation ECU,
via the transponder coil, occur as follows:
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A unique key identification number is passed to the ECU
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A random code is transmitted by the ECU to communicate with the key transponder
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An encrypted response to the random code is transmitted from the key transponder to the ECU.
Programming – Vehicles Up to VIN 242163
The immobilisation ECU is programmed with vehicle specific data during manufacture. The key transponders are
supplied with the specific vehicle pre-programmed with the mechanical code for that vehicle's lockset. The mechanical
code is read at the factory before the keys are programmed and the information is stored in a central database. The
data is required to cut spare or replacement keys.
The ECU is programmed during manufacture with data to support up to ten keys. The programmed information is
recorded against the VIN for that vehicle and stored in a central database.
Replacement or spare keys will be ordered and delivered to the dealer already programmed with the correct
information specific to the particular vehicle and ready for use.
If a replacement immobilisation ECU is required it will be ordered and delivered to the dealer programmed with the
original information stored during manufacture. The ECM will not require reprogramming because the replacement
ECU will have the same identification code as before. The ECM and the EWS-3D immobilisation ECU will however
need have their rolling code synchronised using TestBook/T4.
If the ECM is replaced, the ECM will have to learn the identification code. This is achieved using TestBook/T4. When
the immobilisation ECU receives the correct diagnostic message it will transmit the identification code on a continual
basis until the ignition is switched off. Simultaneously, the ECM also receives a diagnostic command to learn the new
code.