Serial Data Link; Powertrain Control Module (Pcm)/Engine Control Module (Ecm) - Daewoo Nubira User Manual

Data Link Connector (DLC)
When the ignition is ON, a scan tool can switch the immo-
bilizer control unit to the data link connector (DLC) mode
for the purpose of diagnostics, key coding, or ID coding.
ID Code Handling
One of 65,535 possible ID codes is stored in the immobiliz-
er control unit's memory.
The ID code can be erased by using the scan tools'RESET
ID CODE command. When the immobilizer control unit
calculates a new ID code, the PCM/ECM ID code must be
reset to match the immobilizer control unit ID code. To re-
set the ID code, refer to "ID Code Reprogramming."
During diagnostic procedures, the ID code can be read for
comparison with the PCM/ECM ID code by using the scan
tool's READ IMMOBILIZER CONTROL UNIT IDCODE
command.

SERIAL DATA LINK

Serial data can be exchanged between a scan tool, the
powertrain control module (PCM)/engine control module
ECM), and the immobilizer control unit.
The scan tool connection is the data link connector (DLC).
POWERTRAIN CONTROL MODULE
(PCM)/ENGINE CONTROL MODULE
(ECM)
When the powertrain control module (PCM)/engine con-
DAEWOO V–121 BL4
IMMOBILIZER ANTI–THEFT SYSTEM 9T – 11
trol module (ECM) detects that the ignition is being turned
ON, the PCM/ECM waits for a release message from the
immobilizer control unit. If a release message is not re-
ceived within a specified time, the PCM/ECM disables the
engine. The engine is also disabled if the identification (ID)
code transmitted by the immobilizer control unit does not
match the code stored in the PCM/ECM's memory. Immo-
bilization remains in effect until the ignition is turned OFF,
or until battery power is removed.
To prevent the vehicle from being driven, the PCM/ECM
applies the following strategy:
S
The ignition module is put in a bypass mode.
S
The PCM/ECM will not create an electronic spark
timing (EST) output. Therefore, no spark will be
generated by the ignition coil.
S
The PCM/ECM will not enable the fuel pump.
S
The PCM/ECM will not enable the fuel injectors.
S
The PCM/ECM sets diagnostic trouble code (DTC)
53.
Serial data communication is transmitted on a single wire
between the immobilizer control unit and the PCM/ ECM.
During diagnostic procedures or ID code changing, a scan
tool is added to the communication system.
A PCM/ECM with an immobilizer control unit is not ex-
changeable with a PCM/ECM that does not have an immo-
bilizer control unit.