Deactivation and Start - Immobilizer System

Deactivation and start - immobilizer system

Deactivation and start (only cars without the keyless locking system)




To deactivate the immobilizer system, the remote key must be inserted in the ignition. When the start button (3/1) is pressed in, the Central electronic module (CEM) (4/56) transmits the command to the Ignition antenna unit (IAU) (16/65) that the remote key identity must be checked. Ignition antenna unit (IAU) activates the built-in antenna and reads off the identity code from the remote key's transponder. This code is transmitted to the Central electronic module (CEM) and compared with the codes that are programmed in the Central electronic module (CEM). If the read off code from the remote key is in the Central electronic module (CEM), the key is approved.
If the vehicle has an Alcolock (option), an approved breathalyzer test must be performed in order for the handset unit to send an approved signal to the Central electronic module (CEM) to work via the Remote Receiver Module (RRX).
For more information, see Design and Function - Alcoguard (Alcolock), Alcohol Analyzing Start Inhibitor.
Central electronic module (CEM) will then activate voltage supply to the fuel pump module (PEM) (4/83).
Central electronic module (CEM) will, after approval of the remote key, check the signals on the CAN-net regarding the vehicle's speed and the engine's status.
If the vehicle is at a standstill and the engine is not running, the Central electronic module (CEM) will activate voltage feed to Steering column lock module (SCL) (4/102) via an internal relay in Central electronic module (CEM), and then send a command to Steering column lock module (SCL) to unlock the steering column lock.
The vehicle cannot be started until the lock bolt in Steering column lock module (SCL) is in unlocked position. The lock bolt's position is indicated by a switch located in Steering column lock module (SCL) and is connected to Central electronic module (CEM).
If Central electronic module (CEM) should detect that voltage feed to Steering column lock module (SCL) for some reason should become high during driving, a warning message is shown in Driver information module (DIM).
When the ignition is turned on or a start attempt is made (by pressing down a pedal and pressing the start button), the communication is checked between Central electronic module (CEM) and Engine control module (ECM).
Checking is performed to ensure that the correct codes are programmed in both control modules. Engine control module (ECM) also performs a check of the identity of Brake control module (BCM) (4/16) by reading out the serial number from Brake control module (BCM).
This number is compared to a programmed number in Engine control module (ECM).
If these checks are performed correctly, then Engine control module (ECM) activates the ignition system. Engine control module (ECM) also sends a command to Central electronic module (CEM) that the fuel pump should be permitted to continue to operate. Should a problem arise or a check is not approved, then Engine control module (ECM) will order Central electronic module (CEM) to deactivate the fuel pump. Engine control module (ECM) also checks the other parameters that are covered by the function for start inhibitor. If all conditions are fulfilled, then Engine control module (ECM) activates the relay for the starter motor. The engine can then be started.
If any of the above steps should fail, the engine will not start and a message will be displayed in the driver information module (DIM).
The immobilizer system has built-in diagnostic test modes (DTM) to ensure that the engine can be restarted after unintentional stops.