Anti-theft System
NATS Audio Link
Description
The link with the NATS IMMU implies that the audio unit can basically only be operated if connected to the
matching NATS IMMU to which the audio unit was initially fitted on the production line.
Since radio operation is impossible after the link with the NATS is disrupted theft of the audio unit is basi-
cally useless since special equipment is required to reset the audio unit.
Initialization process for audio units that are linked to the NATS IMMU
New audio units will be delivered to the factories in the“NEW”state, i.e. ready to be linked with the vehi-
cle’s NATS. When the audio unit in“NEW”state is first switched on at the factory, it will start up communi-
cation with the vehicle’s immobiliser control unit (IMMU) and send a code (the“audio unit Code”)tothe
IMMU. The IMMU will then store this code, which is unique to each audio unit, in its (permanent) memory.
Upon receipt of the code by the IMMU, the NATS will confirm correct receipt of the audio unit code to the
audio unit. Hereafter, the audio unit will operate as normal.
During the initialisation process,“NEW”is displayed on the audio unit display. Normally though, communi-
cation between audio unit and IMMU takes such a short time (300 ms) that the audio unit seems to switch
on directly without showing“NEW”on its display.
Normal operation
Each time the audio unit is switched on afterwards, the audio unit code will be verified between the audio
unit and the NATS before the audio unit becomes operational. During the code verification process,“WAIT”
is shown on the audio unit display. Again, the communication takes such a short time (300 ms) that the audio
unit seems to switch on directly without showing“WAIT”on its display.
When the radio is locked
In case of a audio unit being linked with the vehicle’s NATS (immobilizer system), disconnection of the link
between the audio unit and the IMMU will cause the audio unit to switch into the lock (“SECURE”) mode in
which the audio unit is fully inoperative. Hence, repair of the audio unit is basically impossible, unless the
audio unit is reset to the“NEW”state for which special decoding equipment is required.
The radio manufacturer has provided their authorized service representatives with so called“decoder boxes”
which can bring the audio unit back to the“NEW”state, enabling the audio unit to be switched on after which
repair can be carried out. Subsequently, when the repaired audio unit is delivered to the final user again, it
will be in the“NEW”state as to enable re-linking the audio unit to the vehicle’s immobiliser system. As a
result of the above, repair of the audio unit can only be done by an authorized representative of the radio
manufacturer.
Service instruction
Item Radio linked with IMMU and/or SECU
Battery disconnection No additional action required
Radio needs repair Repair needs to be done by authorised representative of radio manufacturer since radio cannot
be operated unless it is reset to NEW state, using special decoding equipment
Replacement of radio by new part Radio is delivered in NEW state. If possible, the radio will automatically link up with the immobil-
iser system. If this appears not possible, the audio unit code needs to be manually input
Transferring radio to another
vehicle / replacement of radio by
an‘‘old’’partRadio needs to be reset to NEW state by authorised representative of radio manufacturer
Replacement of IMMU by new part Radio will request for the audio unit code input prior to establishing the link with the IMMU
Replacement of IMMU by old part If a radio code has already been stored in memory of the IMMU, the radio cannot be linked to it.
After switching on the radio, it will display‘‘SECURE’’after 1 minute. Operation can only be
established after resetting the ratio by an authorised representative of radio manufacturer
No communication from IMMU to radio Radio will display‘‘SECURE’’after 180 attempts to communicate with IMMU. Further use of radio
impossible until communication is established again, or after radio is reset by authorised repre-
sentative of (radio) manufacturer
AUDIO
EL-216
