Each connected device adds than its “electric footprint” to the power consumption transients at the root of the network. There is expected only one point in power supply network for measurement in ideal way. The submitted work deals with a design of unusual approach to diagnostics of standard electric devices in vehicles. This concept allows material savings in contrast to the current trends of vehicular diagnostic concept. Vehicular power supply network is used as an information carrier for diagnostic signs provided by the devices. The devices are their own sensors in this principle. The signs come out of the focused devices electric consumption.