ECM DAEWOO LACETTI 2004 Service Repair Manual

9T2 – 4IIMMOBILIZER ANTI–THEFT SYSTEM
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P1626 (MR–140,
HV–240), P1628 (SIRIUS)
ECM IMMOBILIZER ERROR (NO SUCCESSFUL
COMMUNICATION)
Circuit Description
When the ignition is turned ON, the key is tested by the im-
mobilizer anti–theft system. While the key code is being
read by the immobilizer control unit, the engine can start
and run with any key that will turn the lock cylinder. The key
code is read and compared with key codes that have been
stored in the memory of the immobilizer control unit. If a
valid key is detected, the immobilizer control unit sends a
serial data release message to the electronic control mod-
ule (ECM). Included in the release message is an identifi-
cation (ID) code which assures that neither the immobiliz-
er control unit nor the ECM has been substituted to defeatthe system. If the ECM receives an invalid release mes-
sage, the ECM performs the following actions:
S Disables the fuel injector circuit.
P1626, 1628 Will Set When
S The ECM does not receive the signal from the im-
mobilizer control module within 1.260 seconds after
the ignition is turned on.
S The above conditions are maintained until the igni-
tion is switched OFF.
P1626, 1628 Will Clear When
S The ignition switch is turned OFF or the scan tool
TROUBLE CODE CLEAR command is issued.

IMMOBILIZER ANTI–THEFT SYSTEM 9T2 – 5
DAEWOO V–121 BL4
P1626, 1628 – ECM Immobilizer Error
(No Successful Communication)
StepActionValue(s)YesNo
1Connect the scan tool using the following procedure:
1. Insert the cartridge into the scan tool.
2. Turn the ignition switch to the OFF position.
3. Connect the scan tool to the data link connec-
tor (DLC).
4. Connect the scan tool’s power cord to the cigar
lighter socket.
5. Select immobilizer mode on the scan tool.
6. Turn the ignition ON, but do not start the en-
gine.
Is communication established between the scan tool
and the immobilizer control unit?–Go to Step 2Go to ”Commu-
nication Be-
tween Immobi-
lizer and Test
Equipment”
2Read the IMMO & ECM ID CODE message that was
displayed after requesting DIAGNOSIS.
Did the message differ from normal message?
Normal Message –
ECM MODE: LEARNT
IMMO. MODE: LEARNT
VIN CODE: SAME–Go to ”Identifi-
cation (ID)
Code Repro–
gramming”Go to Step 3
3Check for an open serial data wire between the im-
mobilizer control unit and the ECM.
Was the circuit open?–Go to Step 4Go to Step 5
4Repair the open serial data wire between the ECM
and the immobilizer control unit.
Is the repair complete?–System OK–
51. Replace the immobilizer.
2. Reprogram the identification (ID) code. Refer
to ”Identification (ID) Code Reprogramming” in
this section.
Is the repair complete?–System OKGo to Step 6
61. Replace the ECM.
2. Turn the ignition ON, OFF for more than 4 sec-
onds.
3. Turn the ignition ON.
Is the repair complete?–System OK–

9T2 – 6IIMMOBILIZER ANTI–THEFT SYSTEM
DAEWOO V–121 BL4
DIAGNOSTIC TROUBLE CODE (DTC) P1631 (MR–140,
HV–240), P1629 (SIRIUS D4)
ECM IMMOBILIZER ERROR (INCORRECT ANSWER)
Circuit Description
When the ignition is turned ON, the key is tested by the im-
mobilizer anti–theft system. While the key code is being
read by the immobilizer control unit, the engine can start
and run with any key that will turn the lock cylinder. The key
code is read and compared with key codes that have been
stored in the memory of the immobilizer control unit. If a
valid key is detected, the immobilizer control unit sends a
serial data release message to the electronic control mod-
ule (ECM). Included in the release message is an identifi-
cation (ID) code which assures that neither the immobiliz-er control unit nor the ECM has been substituted to defeat
the system. If the ECM receives an invalid release mes-
sage, the ECM performs the following actions:
S Disables the fuel injector circuit.
P1631, 1629 Will Set When
S The ECM receives an incorrect release message
from the immobilizer control unit more than five
times.
P1631, 1629 Will Clear When
S The ignition switch is turned OFF or the scan tool
TROUBLE CODE CLEAR command is issued.

IMMOBILIZER ANTI–THEFT SYSTEM 9T2 – 7
DAEWOO V–121 BL4
P1631, 1629 – ECM Immobilizer Error (Incorrect Answer)
StepActionValue(s)YesNo
1Connect the scan tool using the following procedure:
1. Insert the cartridge into the scan tool.
2. Turn the ignition switch to the OFF.
3. Connect the scan tool to the data link connec-
tor (DLC).
4. Connect the scan tool’s power cord to the cigar
lighter socket.
5. Turn the ignition ON, but do not start the en-
gine.
Is communication established between the scan tool
and the immobilizer control unit?–Go to Step 2Go to ”Commu-
nication Be-
tween Immobi-
lizer and Test
Equipment”
21. Select DIAGNOSIS from the scan tool menu.
2. Read the IMMO & ECM ID CODE (immobiliza-
tion and electronic control module identification
code) message.
Did the message differ from normal message?
Normal Message –
ECM MODE:LEARNT
IMMO. MODE: LEARNT
VIN CODE: SAME–Go to ”Identifi-
cation (ID)
Code Repro–
gramming”Go to Step 3
31. Replace the ECM.
2. Reprogram the ID code.
Is the repair complete?–System OKGo to Step 4
41. Replace the ECM.
2. Turn the ignition ON, OFF for more than 4 sec-
onds.
3. Turn the ignition ON.
Is the repair complete?–System OK–

IMMOBILIZER ANTI–THEFT SYSTEM 9T2 – 9
DAEWOO V–121 BL4
MAINTENANCE AND REPAIR
ON–VEHICLE SERVICE
KEY CODING PROCEDURE
1. Install the immobilizer control unit cartridge in the
scan tool.
2. Turn the ignition off
3. Connect the scan tool
4. Turn the ignition on with the key to be coded
5. Enter the four–digit password that enables service
personnel to use the scan tool for key coding.
6. Use the scan tool command.
7. Verify that the key coding was successful by start-
ing the engine with each of the authorized keys.
ID CODE REPROGRAMMING
Reprogram the identification (ID) code in the following si-
tuations:
S An immobilizer control unit has been replaced.
S An electronic control module (ECM) has been re-
placed.
If a valid key has been lost, refer to ”Key Coding Proce-
dure” in this section.
TRANSPONDER
Each valid ignition key has an internal transponder which
is a read /write transponder.
The transponder contains an implementation of a crypto–
algorithm with 96 bits of user configurable secret–key con-
tained in EEPROM and transmits data to the ICU by mod-
ulating the amplitude of the electromagnetic field, and
receives data and commands in a similar way.
IMMOBILIZER CONTROL UNIT
Removal Procedure
1. Remove the imstrument panel lower cover.

IMMOBILIZER ANTI–THEFT SYSTEM 9T2 – 11
DAEWOO V–121 BL4
GENERAL DESCRIPTION
AND SYSTEM OPERATION
IMMOBILIZER SYSTEM
The purpose of the Immobilizer system is to provide addi-
tional theft deterrence to the vehicle in which it is installed
and to prevent it from being stolen or driven by unautho-
rized users.
The verification of the user authorization is done by an igni-
tion key with integrated transponder.
The external LED displays the Immobilizer status and has
an additional theft deterrence function.
To secure the communication, the status is exchanged be-
tween the Immobilizer and the ECM in a 5 byte of encoded
data.
These 5 bytes are composed by a mixture of random data
and two types of fixed code
S a vehicle model identification number : MIN
S a vehicle specific identification : VIN
The MIN is known from the first supply of the system.
The VIN is realized by ICU on the special order from the
key coding (reading of transponder code and storing it as
valid key code in Immobilizer EEPROM).
A different random data is computed at each key transi-
tion.
All the immobilization communication between the ECM
and ICU is made on K–line (K line : Serial data line ’7’).
Due to the learning of the Vehicle specific identification
Number, both ICU and ECM can stay in 3 stable modes
S Virgin mode (VIN not learnt)
S Learnt mode (VIN learnt)
S Neutral mode (for a new VIN learning)
In case of using valid key, the release message commu-
nication with the ECM take place and the LED displays the
Immobilizer status valid key In case of using invalid key,
the ECM disables the fuel injector circuit with coded inter-
vention and sets DTC(Diagnostic Trouble Code)
The above conditions are maintained until the ignition is
switched off.
An ECM without an immobilizer control unit cannot be in-
terchanged for an ECM that is used with an immobilizer
control unit system. The Immobilizer control unit and ECM
must have a matching ID code. ID coding and key coding
are accomplished by using Scanner–100
The Immobilizer system consists of
S a maximum or 5 ignition keys with integrated trans-
ponder
S the toroidal coil (Detection coil) for energizing and
reading the transponder mounted at the ignition
lock.S the Immobilizer control unit(ICU) with :
– power supply
– ignition input circuit
– transponder modulation and demodulation unit
– EEPROM
– driver electronic for the external status LED
– serial data link hardware
S the external status LED for displaying the Immobi-
lizer status
S the serial data link between Immobilizer and ECM
ELECTRONICALLY CODED KEYS
Each valid ignition key has an internal transponder which
is a read /write transponder.
The transponder contains an implementation of a crypto–
algorithm with 96 bits of user configurable s cret–key con-
tained in EEPROM and transmits data to the ICU by mod-
ulating the amplitude of the ele tromagnetic field, and
receives data and commands in a similar way.
DETECTION COIL
The toroidal coil is mounted at the ignition lock in front of
the key barrel.
It is connected to the ICU with a four terminal connector
fixed at the body of the coil.
The length of the connection between coil and Immobilizer
is restricted to 50cm. The correct placement on the ignition
lock and the exact electrical data is very important for the
reading distance of transponder.
he toroidal coil and receiving coil inside the transponder
built a transformer. During the readingprocess the coil in-
duces energy into the transponder. The transponder
charges the field and generates an amplitude modulated
signal with the manchester coded data. This charge of the
field is demodulated inside the Immobilizer.
The Immobilizer contains the coil driver hardware for di-
rect connection of the toroidal coil.
IMMOBILIZER CONTROL UNIT
The function of the Immobilizer System is shared between
the ICU and the ECM.
The task of the Immobilizer Electronic Control unit (ICU)
are:
S Reading of the input information ”ignition ON/OFF”
S Controlling the states LED
S Controlling the transponder read/write process
(modulation, demodulation, decoding, comparison
of the read code with the code of the valid keys).
S Communication with the ECM after ignition ON (re-
ceiving of the ECM–request and transmission of
release message).
S Special functions for calculation and handling of the
VIN–code.
The VIN code is calculated by the Immobilizer using a ran-
dom generator.

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.

IMMOBILIZER ANTI–THEFT SYSTEM 9T2 – 13
DAEWOO V–121 BL4
1. After receiving a response message including the
information ”ICU in learnt mode” and the correct
system VIN–code

the ECM enters the release state, which al-
lows to continue the running of the engine.
2. After receiving a response message including the
information ”ICU in learnt mode” and a wrong sys-
tem VIN–code

the ECM does not send a new request and
enters the blocked state, which causes the ac-
tivation of the immobilization actions of the en-gine.
3. If the ECM doesn’t receive a response message
within a defined time from beginning of the release
time period or the ECM receives a no release an-
swer

the ECM enters the blocked state, which
causes the activation of the immobilization ac-
tions of the engine.
S The inactive state of the Immobilizer (valid key/
invalid key) ends with turning off the ignition.