15.4.4. Detection of bad grounding
The negative plug of the accumulator is connected to "weight" — to metal 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, at the same time current comes back to the accumulator through body metal. 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 or bad 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 also work of one chain can have effect imperceptible at first sight on work of other chain. 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 pt direct contact between metal elements, because of soft rubber fastenings or a paint coat.
For check of reliability of grounding of an element, it is necessary to switch-off the accumulator and to connect one of ohmmeter probes to reliably grounded element. Connect other probe to a pla wire to 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.
If you assume lack of grounding, investigate connection and 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 put a layer of vaseline or silicone lubricant.