9T2 – 12IIMMOBILIZER ANTI–THEFT SYSTEM
DAEWOO V–121 BL4
The VIN code is transmitted from the Immobilizer in the re-
lease message communication only incase of using an au-
thorized key. Without an authorized key it is not possible
to getthe system VIN code.In case of ECM internal state
is in Virgin mode or neutral mode the ECM learns the sys-
tem VIN code automatically after receiving the first release
response message.
To get a synchronized Immobilizer system (same VIN–
code in Immobilizer and ECM,authorized key) the DLC
test equipment has to be used for authorization of the
keys(first key coding). The usage of this test equipment is
restricted to authorized persons.
S Communication with the DLC–test equipment. Main
functions are the key coding procedure, the VIN–
code handling and the support for system test func-
tions.
S Handling of the software watchdog
Operation
In the active mode of immobilizer (engine OFF, IG key
OFF) the status LED isblinking as mode A. When ignition
is turned ON, the system wakes up and tries to read out
the transponder.
In case of the detection of a valid key , The release mes-
sage communication with the ECM takes place. The sta-
tus LED displays the Immobilizer state ”valid key”.
After turning off the ignition(ignition OFF detection similar
to the ECM ignition OFF detection), the Immobilizer
changes to the active mode. The status LED is blinking as
Mode A.
Data Link Connector (DLC) Mode
When the ignition is on, a scan tool can switch the immobi-
lizer control unit to the DLC mode for diagnostics, key cod-
ing and ID coding.
S The status LED is turned off during DLC–mode
S The Immobilizer will answer all correct messages,
which are defined as Immobilizer messages.
ID Code Handling
One of 65,535 VIN codes is stored in the immobilizer EE-
PROM.
The VIN code can be erased by using ”Reset VIN code”
command of the scan tool.
When the immobilizer control unit calculates a new VIN
code, ECM VIN code should be reset to get identical with
the immobilizer control unit’s.
During diagnostic procedures, the VIN code can be read
for comparison with the ECM VIN code by using the scan
tool’s ”Read immobilizer control unit VIN code” command.
SERIAL DATA LINK
Serial data can be exchanged between a scan tool and the
ECM and the Immobilizer control unit.
ELECTRONIC CONTROL MOUDLE
(ECM)
S ECM in Virgin mode
In this mode, the ECM knows only the model
vehicle identifier code.
The engine can be locked/unlocked.
ECM requests to ICU the VIN number. As soon
as the ECM receives two correct consecutive
communication frames with the same VIN code
the ECM learns it.
The VIN code will be stored in non–volatile
memory at the end of power latch phase. ECM
enters in Learnt mode.
S ECM in Learnt mode
In such a state, ECM checks on every commu-
nication, the correct encoding of the ICU.
If the code received is not correct, then the vehicle is im-
mobilized.
The coded 5 bytes of data emitted by ECM are
a mixture of MIN code and random.
The coded 5 bytes of data emitted by ICU are a
mixture of VIN code and random.
S ECM in Neutral mode
This mode is a special intermediate mode, used
for ICU replacement or immobilizer option instal-
lation.
ECM request to ICU the VIN number. As soon
as the ECM receives two correct consecutive
communication frames with the same VIN code
the ECM learns it. The VIN code will be stored
in non–volatile memory at the end of power latch
phase. ECM enters in Learnt mode.
S After turning on the ignition the ECM will control the
engine in a normal way for starting and running
while waiting for a valid release response message
from the Immobilizer.
