15.3.1. Detection of a rupture of a chain

15.3.2. Detection of a source of short circuit

15.3.3. Detection of bad grounding

The electric chain consists of the electric element, switches, the relay, safety locks, automatic switches, wires and sockets connecting an electric element to the rechargeable battery and "weight". For the help by search of sources of malfunction of system of electric equipment at the end of the management schemes of electric equipment of the car are provided.

Before trying to define a malfunction source, attentively study the corresponding scheme of electric equipment to gain an impression about the elements established in this chain. Often the cause of defect can be defined, having checked functioning of other elements entering this chain. If several elements or chains fail at the same time, then the problem, obviously, consists in malfunction of a safety lock, the general for these chains or elements, or contact with a body.

Malfunction of electric equipment is quite often caused by such simple reasons as the weakened or rusted sockets, lack of contact with a body, the fused safety locks, the melted burned-through crossing point or the faulty relay. Surely carry out a visual inspection of a condition of all safety locks, wires and sockets in the failed chain before starting check of other elements. Use schemes of electric equipment for definition of what of trailer clips need to be checked for detection of a source of malfunction.

The main tools necessary for detection of a source of malfunction, the tester or the voltmeter are (a bulb on 12 V and couple of wires with probes on the ends can be also used for conducting some checks); ohmmeter; the battery and a set of the wires equipped with probes; a cap puncture (it is desirable with the automatic switch or a safety lock which is used for a round of the checked wires or elements).

For detection of the reason of unreliable work any of elements (usually because of bad connection or pollution of contacts, or the damaged isolation), it is possible to carry out an inspection simple stirring of wires. It is necessary to shake a wire by a hand to check whether malfunction at the movement of a wire has an effect. By this elementary method it is possible to narrow a circle of search of possible sources of malfunction to a minimum.

Along with problems of bad connection of wires, in system of electric equipment there are two main types of malfunctions — disconnection of a chain or short circuit.

Problems with the opened chain appear as a result of break in electric equipment chain that interrupts course of current. The opened chain will entail shutdown of an element of electric equipment.

The second problem is caused by short circuit of the site of a chain that leads to leakage of current of other chain, usually directly on a body. The most probable cause of short circuit — violation of isolation of wires. Short circuit usually leads to burn-out of the corresponding safety lock.