At diagnostics of an electric chain to find in it a cause of defect it appears quite difficult as survey of plugs on existence of corrosion or violation of quality of their contacts is complicated in a type of limitation of access to them (usually plugs are closed by the case of the electric socket). Sharp or a plait of wires in many cases leads twitchings of the case of the socket on the sensor to contact restoration. Unstably arising refusals can have the reason oxidation of plugs or violation of quality of contacts.