Passive Deactivation and Start - Immobilizer System
Passive deactivation and start - immobilizer system
Passive deactivation and start (only cars with the keyless locking system)
To carry out a start of a keyless vehicle, a pedal must be depressed (clutch (MAN) or brake (AUT)) and the starter button pushed. When the starter button is pushed, an input on the keyless vehicle module (KVM) (4/93) is supplied with voltage, which searches for a remote key with passive function in the vehicle. Ground connection from the starter button also goes to the Central electronic module (CEM) (4/56), which, at the same time, transmits an encrypted request to the Keyless vehicle module (KVM). This request is responded to only if an approved passive remote key has been registered. If a remote key is found, the keyless vehicle module (KVM) checks that it is approved. If this is the case, the keyless vehicle module (KVM) transmits a response to the central electronic module (CEM) indicating that the remote key is approved.
If a passive remote control key cannot be found then the central electronic module (CEM) will instead send a request to the Ignition antenna unit (IAU) (16/65) to scan for a transponder. If an approved transponder is identified then the central electronic module (CEM) will approve the key.
If a start attempt is made, either non-keyless or keyless, the Central electronic module (CEM) will 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, then Central electronic module (CEM) will activate voltage feed to Steering column lock module (SCL) (4/102) via an internal relay and will 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 its 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). During driving, continuous checking is performed of the Central electronic module (CEM) to make sure that the steering column lock is not activated accidentally.
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 checks 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.