The typical electric chain consists of an element of electric equipment, switches, the relay, engines, safety locks, the burned-through crossing points or automatic switches and wires and connections which connect all elements among themselves and connect them to the accumulator and mass of the car.

Before check of a faulty chain, study the schematic diagram of this chain in the beginning to understand of what elements it consists. The source of malfunction can be found quicker if to define what of elements of this chain work normally. If several elements or chains fail at once, the problem probably consists in the fused safety lock or bad grounding as often one safety lock is responsible for several chains.

Problems with work of system of electric equipment are usually caused by the simple reasons, such as the oxidized or unreliable contacts, the fused safety lock, the fused burned-through crossing point or the faulty relay. Visually check a condition of all safety locks, wires (if it is possible) and connections in a faulty chain before check of other elements of this chain. If you are going to use instrumentations, use schematic diagrams to define what connections need to be checked for failure detection.

The main devices necessary for search of malfunction in electric equipment chain, are the voltmeter (or a bulb on 12 Volts with connecting wires), the device for check of integrity of chains, the accumulator with connecting wires and a cap wire, it is desirable with the automatic switch which can be used for parallel connection to a chain. 

Before search of malfunction with use of the control and measuring equipment, study schematic diagrams to define connection points.