There are two types of
immobilizer functions available on the Body Control Module (BCM). The
first is a "SMARTRA (SMART TRansponder Antenna)"type and the second is a
"stand alone" type that will emulate the system known as the "SCE
immobilizer". The hardware to support both types of immobilizer systems in
the BCM is identical. The selection of immobilizer type withinthe BCM is
effected by setting the appropriate EEPROM byte.
All communications
between the BCM and the ECM (Engine Control Module) for the purposes of
immobilization will be over the W line.
The diagnostics
communication for the SMARTRA system will be performed by communicating
with the ECM on it's K line. The ECM will then perform diagnosticson the
BCM via the W line.
At the time of
Transponder validation, the BCM devotes 100% processing power to the
validation process in order to respond in the required time.During
transponder validation, other BCM functions may be
influenced.
1. |
SMARTRA type
immobilizer
The "SMARTRA" type immobilizer system is
applied to the 2.0β engine.
The immobilizer system consists of a passive
challenge-response (mutual authentication) transponder inside the
key head, a stand alone antenna, the BCM unit and the ECM. The BCM
unit shall emulate the original SMARTRA immobilizer as closely as
possible. In this document, the BCM emulating the originalSMARTRA
shall just be known as SMARTRA.
In the SMARTRA system, the immobilizer is
contained within the ECM. The BCM shall provide the low-level
routines and hardware necessary to communicatewith the
transponder. |
2. |
Stand alone type
immobilizer
The "Stand alone" type immobilizer system is
applied to the 2.7δ engine.
The immobilizer system consists of a passive
challenge-response (mutual authentication) transponder inside the
key head, a stand alone antenna, the BCM unit and the ECM. The BCM
unit shall emulate the original SCE type immobilizerto ECM protocol
as closely as possible.
In the Stand alone immobilizer system, the
immobilizer is contained within the BCM. The ECM shall request the
BCM for permission to start the vehicle. The BCM shall perform the
immobilisation functions and reply "start"or no start" permission to
the ECM. |
SYSTEM BLOCK DIAGRAM

1. |
Engine Control
Module (ECM) States
The ECM has three defined states. These are
described below.
State
|
Description
|
Virgin
State
|
•
|
The ECM is delivered to HMC in
virgin state |
•
|
There is no Vehicle Identification
Number (VIN) stored in the
ECM |
•
|
It can only be in virgin state
once |
•
|
The ECM will allow starting on the
second cycle of
ignition |
•
|
Virgin state is exited when a VIN
has successfully been taught by the
BCM | |
Learnt
State
|
Engine
start is possible only when the received VIN from the BCM
matches that stored in the ECM
|
Neutral State
|
•
|
Same as virgin state except engine
starting not possible on the second cycle of
ignition |
•
|
Neutral state is entered if the
BCM changes to neutral
state | |
|
2. |
Body Control Module
(BCM) states
The Body Control Module (BCM) has three
defined states. These are described below.
State
|
Description
|
Virgin
State
|
•
|
The BCM is set to virgin state
during manufacture |
•
|
The BCM can be set back to virgin
state by issuing an 'Initiate BCM'
command |
•
|
The diagnostics password is set to
the default |
•
|
Virgin state is exited only after
the VIN been
learned | |
Learnt
State
|
The BCM
contains a VIN
|
Neutral State
|
•
|
The BCM is set to neutral state by
issuing a 'Teaching ECM'
command |
•
|
The purpose of the neutral state
is to allow the ECM to be set to neutral
state |
•
|
The BCM neutral state expires 10
seconds after an ignition ON→OFF
cycle | |
|
TEACHING PROCEDURES
THE USER PASSWORD CAN BE IN THE STATUS
LIMP HOME FUNCTION
The password and the pin code are not the
same. Pin code is scanned from a bar code at the End Of Line (EOL).
The passwordis a number chosen by the owner for the purposes of limp
starting.

|