Control module
The immobilizer control module is located above the integrated relay/fusebox to the left of the driver. The casing of the immobilizer control module has different colors. The color depends on which type of engine control module (ECM) it is intended to communicate with.
The engine control module (ECM) cannot activate the fuel injection system when the immobilizer system is inactive. This means that the engine cannot start. To further increase the security the ground to the starter relay is also disconnected. This means that the starter motor cannot be turned.
When the system is activated the immobilizer control module transmits an instruction to the engine control module (ECM) to activate the fuel injection system and to ground the control circuit on the starter relay.
The immobilizer control module communicates with the ignition key transponder via an antenna ring around the ignition switch.
To increase the security and incorporate the components of the system the immobilizer control module must be programmed with three codes before it can be used:
- PIN code to program the key
- code for the engine control module (ECM)
- code for communication with the VGLA (Volvo guard lock and alarm system) control module.
These codes are entered automatically when programming a new control module.
The immobilizer control module also contains a unique identification code (PIN-code). This PIN code is used when making modifications to the system. For example programming new keys or erasing keys if the old ones have been stolen or lost.
The immobilizer system cooperates with the VGLA (Volvo guard lock and alarm system) control module by transmitting a signal to deactivate the alarm if the correct key is inserted in the ignition switch. Each key is programmed with a unique identification code so that the immobilizer control module can recognize each key. This happens at the end of the manufacturing process of the vehicle. These codes must then be learned by the immobilizer control module. The immobilizer control module can be programmed to recognize up to 6 keys.
The immobilizer control module has built-in diagnostics and diagnostic trouble codes (DTCs) can be read out using VIDA. The immobilizer control module also contains a monitoring function for the connection between the immobilizer control module and the engine control module (ECM). The monitoring function can detect open-circuits, short-circuits to ground or short-circuits to supply voltage.
The immobilizer control module has continuous power supply (+30) from the battery and is grounded via the connection rail (15/6).