Serial communication

ECM (Engine Control Module) communicates serially with the following:

Immobilizer 

The request and exchange of information between the engine control module (ECM) and the Immobilizer.

All serial communication between the data link connector (DLC) and the engine control module (ECM) passes through the Immobilizer control module.

Data Link Connector (DLC) 

The serial communication via the data link connector (DLC) (pin 7, C-line) is used for reading off Volvo on-board diagnostic (OBD) system  and by the authorities and certain other workshops in the USA/CDN for reading off OBD II codes using the Generic Scan Tool.