The negative plug of the accumulator is connected to "weight" — to metal massive unpainted parts of a body, the engine or transmission. At the same time many elements of electric equipment are connected in such a way that only the positive wire approaches them, and current at the same time comes back to the rechargeable battery through a body. It means that fastening of an element of electric equipment and a body are a part of an electric chain. Thereof the bad or rusted fastening can cause failure in the functioning of an element or lead to its unstable work. In particular, bulbs can burn with dim light (especially if in a point of grounding of this bulb grounding any else the switched-on electric equipment element is carried out), electric motors can slowly work, and work of one chain can make impact imperceptible at first sight on work another. Do not forget that on many cars grounding wires between some elements such as engines/transmissions and a body are used, that is in those places where direct contact between metal elements because of soft rubber fastenings or a paint coat is absent.

For check of reliability of grounding of an element it is necessary to switch-off the rechargeable battery and to connect one of ohmmeter probes to reliably grounded element. Connect other probe to a wire or connection with a body which needs to be checked. Resistance shown by an ohmmeter has to be equal to zero — if is not present, check connection as follows. Clear the site of a body and the plug of a wire (or the surface of grounding of an element) to pure metal. Carefully remove all traces of dirt, then by means of a knife peel all paint so that the reliable contact of two metal surfaces turned out. At assembly reliably delay fastening of the socket. At connection of the plug of a wire establish a washer with rough edges between the plug and a surface of a body for ensuring reliable connection. At connection prevent emergence of corrosion in the future, having applied a layer of vaseline or silicone lubricant on this site.