Diagnostic device for monitoring a sub-system in a motor vehicle

摘要

The invention relates to an on-board or off-board diagnostic device (1) enabling a vehicle manufacturer or the like ("clients") to carry out a client diagnosis (N) or to monitor a motor vehicle sub-system (2) manufactured by a special supplier, using the vehicles's data collection line (3) or data bus and comprising an electronic control device allocated to said sub-system (2) which is connected to an operating unit (5) for instance, by means of a line (HS). According to the invention, a specially coded signal (S) is fed into the electronic control device (4) in order to switch from client diagnosis mode (N) to special supplier diagnosis mode (U) so as to provide extended or modified sub-system (2) data on an already existing line (HS).