Diagnostic Functions

Diagnostic functions

General
The master unit for the immobilizer system is the central electronic module (CEM). This is also the module which stores diagnostic trouble codes (DTC) for faults in the immobilizer system. For information about diagnostic functions, see Design and Function, central electronic module (CEM).

Programming
To increase the security of the immobilizer system, the following control modules are linked to each other with codes.
- central electronic module (CEM)
- engine control module (ECM).
- Keyless vehicle module (KVM) (only vehicles with the keyless locking system)
- ignition antenna unit (IAU)
- steering Column Lock Module (SCL) (does not apply to USA/CAN-market).
Codes must be programmed when replacing the control module in order for the vehicle to start. Furthermore, the serial number for the Brake control module (BCM) is checked by the Engine control module (ECM) before the Engine control module (ECM) permits the vehicle to start. This requires that the serial number in the Brake control module (BCM) be entered into the Engine control module (ECM) when replacing the Brake control module (BCM) or replacing the Engine control module (ECM). This occurs automatically when downloading software into the new control module.

Programming remote keys
Remote keys can be added and erased. When programming remote keys for a vehicle, the transponder and remote control are programmed at the same time. A maximum of 6 transponder IDs and their remote control keys can be programmed into the vehicle. The transponder and remote control IDs are stored in the central electronic module (CEM) in cars without the keyless locking system.
In cars with the keyless locking system, only the transponder ID is stored in the central electronic module (CEM). ID of the keyless function is stored in the keyless vehicle module (KVM) and also saved in the Central electronic module (CEM).
The erase function is used when the customer wishes to prevent one or more remote keys from being used to start the vehicle. The remote keys may have been stolen and could be traced back to the vehicle.
Remote keys are programmed via the Software Manager.

Reading off the number of programmed remote keys
The number of programmed remote keys that are stored in the Central electronic module (CEM) can be read off via the menu system in the Infotainment display. For further information, see the vehicle's user manual.

Programming the handset unit for the Alcolock (option)
See Design and Function - Alcoguard (Alcolock), Alcohol Analyzing Start Inhibitor.