The usual electric chain consists of an electric element, switches, the relay, engines, safety locks, automatic switches, wires and sockets which connect an electric element to the storage battery and a body. For the help by search of sources of malfunction of system of electric equipment schemes of electric equipment of the car are provided in the management.

Before trying to define a malfunction source, study the corresponding scheme of electric equipment for receiving idea of elements in this chain. The number of possible sources of malfunction can be reduced if to check work of other elements entering into this chain. If some elements or chains fail at the same time, possibly, the safety lock, the general for these chains or elements is faulty, or connection with a body – "weight" is broken.

Causes of defect are the weakened or oxidized sockets, violation of contact to a body, the fused safety locks or faulty relays. Visually check a condition of all safety locks, wires and sockets in the failed chain before to start check of other elements. Use electric equipment schemes for definition of places of possible malfunctions which are necessary for checking for detection of a source of malfunction.

The main devices necessary for detection of a source of malfunction, the tester or the voltmeter, a control lamp on 12 are in, an ohmmeter, the battery and a set of wires with щупами, a cap puncture, it is desirable with the automatic switch or a safety lock which is used for round of checked wires or elements.

Except bad connection of wires in system of electric equipment two more main types of malfunctions — the opened chain or short circuit are possible.

The chain is disconnected as a result of break in an electric equipment chain that interrupts a current, causing shutdown of an element of electric equipment.

For check of an integrity of a chain connect the device for verification of schemes or the voltmeter: one conclusion to the negative plug of the storage battery or the earthed element, another — to contact in a checked chain, it is desirable for the next to the storage battery or a safety lock. Thus checked site of a chain should be energized from the storage battery, except for a case when the connection socket to the battery does not carry out a current or fused a safety lock (do not forget that some chains of electric equipment join only at key turn in the ignition lock in a certain situation).

Include the chain, then connect щуп a tester to the connection closest to the switch of a chain on the party of the checked element.

If there is a tension (to what fire of a control lamp or the voltmeter indication testifies), means, in a chain site between the corresponding connection and the switch there are no gaps.

If the site on which there is no tension is found, means, break of a chain occurred between this point and a point of the previous check on which there was a tension. Break of a chain is caused by the damaged or weakened socket.

The following consumers of the electric power can be possible sources of short circuit: lamps, electric motors, heating elements, etc.

Remove the corresponding safety lock and connect tester or voltmeter conclusions to safety lock plugs.

Include a food in chains, thus do not forget that some chains of electric equipment join only at key turn in the ignition lock in a certain situation.

If in a chain there is a tension, means, in a chain there was a short circuit.

The negative plug of the storage battery is connected to "weight" — to a body, the engine or a transmission. The unreliable or oxidized fastening can lead to refusal of an element or violation of its work. Do not forget that on many cars "mass" wires between some elements, such as the engine, transmission with a body, that is in those places where there is no direct contact between metal elements because of soft rubber fastenings or a paint coat are used.

For check of reliability of grounding of an element disconnect the storage battery and connect one of ohmmeter conclusions to reliably earthed element. Connect other conclusion to a wire or connection with a body which is necessary for checking. Resistance shown by an ohmmeter should be equal to zero if is not present, check connection as follows: if raises doubts reliability of contact to "weight", disassemble connection, remove pollution and smooth out contacts. At assembly tighten socket fastening, having put a layer of technical vaseline or silicone greasing for corrosion prevention.