Search of causes of failures of electric equipment

General information

The typical electric contour consists of the consumer of the electric power (a working element), a set of switches, the relay, executive electromotors, safety locks, the fusible inserts/breakers of a chain concerning work of this element, and also connecting electroconducting, its contact plugs and sockets. For the purpose of simplification of performance of diagnostic procedures schemes of electric connections of systems of onboard electric equipment are provided in Schemes of electric connections at the end of the Management.

Before starting search of causes of failure of the failed consumer of the electric power, attentively study the corresponding electric circuit, try as it is possible to imagine more clearly a principle of functioning of the elements which are a part of the suspected contour. The list of possible causes of failure can be minimized by a way of an exception of it regularly functioning components concerning work of the checked contour. At simultaneous violation of functioning at once several components, the most probable cause of refusal is failure of the general for the corresponding chains insert safety lock/melting, or grounding violation.

More often refusals of electric equipment speak the elementary reasons, such as oxidation, or weakening of fastening of terminal connections, failure of a safety lock or a fusible insert, failure of the relay, etc. Before starting search of internal defects of actually refused component, attentively study a condition of all safety locks concerning its functioning, sockets and connecting wires.

For definition of the list of knots subject to check and contact sockets, study the corresponding schemes of electric connections (see. Schemes of electric connections).

To number of the diagnostic devices more often used by search of refusals of electric equipment, it is necessary to carry a universal measuring instrument the chain/voltmeter (also usual 12-voltny lamp will be suitable for some checks with a set of connecting wires), a lamp sampler with the individual power supply (sometimes called also a conductivity measuring instrument), an ohmmeter, the power supply with a set of connecting wires, and also a set of the wires crossing points, equipped various type connecting plugs and - it is desirable - the built-in breaker a chain/safety lock (for shunting of suspicious sites of a chain or electric components). Before connecting the diagnostic equipment, attentively study the scheme of electric connections of components of the corresponding contour (see. Schemes of electric connections).

At identification of the reason of refusal having unstable character (violations such as a rule appear connected with oxidation of contact plugs, or weakening of fastening of terminal connections of electroconducting) the simplest check of a chain which is carried out by twitching of various sites of electroconducting of the corresponding contour as a result of which the defective piece of a chain is localized can be made. This check can be made together with any of listed below in the corresponding subsections.  

Except the problems connected with violation of quality of electric connections, it is necessary to refer breaks and short circuits to number of the most probable and often occurring refusals of electric contours in a chain.

Chain break usually is caused by mechanical injury of tokoprovodny veins, or a detachment of contact plugs that leads to disconnection of a contour and the circulation termination in it an electric current. As a result of chain break its working component ceases to function, however the corresponding safety locks / fusible inserts do not fail.

Short circuit of its electroconducting is called as short circuit unforeseen a chain design. Thus the current starts to circulate on the shortest way, in most cases leaving on weight. Short circuits appear connected with violation of integrity of isolation of electroconducting more often and without fail lead to failure of the corresponding safety locks / fusible inserts.

Tension stock-taking in a chain

Stock-taking of tension is included into number of standard checks in default any consumer of the electric power. Connect one of wires («-») a chain/voltmeter measuring instrument to the negative plug of the battery, or any of reliably earthed points on the car chassis/engine. The second wire of the device connect to the terminal connection of a checked contour preferably closest to the battery or a safety lock. Submit a food to a contour, - do not forget that some chains запитываются only in certain positions of the switch of ignition. If tension takes place (the measuring instrument lamp joins, or on the indicator of the voltmeter the corresponding indication is fixed), the chain piece between checked terminal connection and the battery means is serviceable.

Continue check, serially passing from one terminal connection of a chain to another, moving in the direction from a battery/safety lock. The faulty site of a contour will settle down between a point on which the device will not register existence of tension and the next tested servicea