A method for monitoring controller area network (CAN) on a mobile system includes identifying links and associated nodes between all the nodes of the CAN, and ranking all the links according to their order of connection to the monitoring controller, including assigning lower ranks to ones of the links proximal to the monitoring controller and assigning higher ranks to ones of the links distal to the monitoring controller. For each of said links, the associated node distal to the monitor is identified. The on-board monitoring controller determines a fault signature for each of the links starting with the link having the highest ranking, said fault signature comprising identified ones of the associated nodes distal to the monitor for each of the corresponding links.