Citroen Xantia

Since 1993 of release

Repair and car operation

Search of causes of failures of an electric equipment

The general information

The typical electric contour consists of the electric power consumer (a working component), switches of management (keys), the relay, drivers electromotors, safety locks, the fusible inserts/breakers of the chain concerning work of the given component, and also connecting electroconducting, its contact plugs and sockets. For the purpose of simplification of performance of diagnostic procedures in last section of the given Chapter schemes of electric connections of various systems of an electric equipment of the car are resulted.

Before to start revealing of causes of a failure of the failed electric device, attentively study the corresponding electric scheme. Try as it is possible to imagine more clearly a principle of functioning of the components which are a part of the given contour. The list of possible causes of a failure can be shown to a minimum by an exception of it of the unequivocally regularly functioning components concerning work of the checked chain. At simultaneous infringement of functioning at once several components or contours, most a refusal plausible reason is failure of the general for the given contours of a safety lock, or grounding infringement.

More often electric equipment refusals speak the elementary reasons, such as oxidation or fastening easing клеммных connections, failure of a safety lock or a fusible insert, relay refusal, etc. Before to start search of internal defects of actually refused component, attentively check up a condition of all safety locks concerning its functioning, contact sockets and electroconducting. For definition of the list of knots subject to check and клеммных connections study the corresponding electric scheme (Removal and installation of components of a pillow of safety see).

It is necessary to carry to number of the basic tools necessary by search of refusals of an electric equipment:
   a) the Measuring instrument of a chain or the voltmeter (for some checks usual 12-voltnaja the lamp with the complete set of connecting wires also will approach);
   b) the Lamp-sampler with the individual power supply (sometimes named also a conductivity measuring instrument);
   c) the Ohmmeter;
   d) the Battery;
   e) the Complete set of connecting wires;
   f) the Set of the wires-crosspieces, equipped various type connecting plugs and, it is desirable, equipped with the breaker of a chain or a safety lock (for shunting of suspicious sites of a chain or electric components).

Before to start actually performance of checks, attentively study corresponding Schemes of an electric equipment.

The elementary check of a chain which are carried out by twitching of various sites of electroconducting of the corresponding contour can be made for search of the reason of refusal having astable character (refusals such usually appear connected with oxidation or fastening easing клеммных connections). As a result of such check it is possible to localise a defective piece of a chain. The given check can be made in addition to any of listed more low in corresponding subsections.

Except the problems connected with infringement of quality of electric connections, it is necessary to carry breakages and short circuit to number of the most probable and often meeting refusals of electric chains.

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

As short circuit is called unforeseen a design of a chain short circuit of its electroconducting. Thus the current starts to circulate on the shortest way, usually leaving on weight. Short circuits are connected with infringement of integrity of isolation of electroconducting more often and without fail lead to failure of safety locks / fusible inserts of protection of a chain.

Search of breakages of a chain

Revealing of the reasons of short circuit

Revealing of infringements of grounding

The negative plug of the battery is earthed on metal of the power unit named in "weight", the chassis and кузовных car elements. Electric contours большей electric equipment parts are constructed in such a manner that connecting electroconducting is used only for food giving to the consumer from the positive plug of the battery, return of a current to the battery is carried out on weight metal. It means that fixing elements of consumers form themselves a returnable part of a chain. In view of the aforesaid, easing of fastening or development of corrosion of basic elements of a working component of a chain involves infringement of serviceability of functioning of a contour from a full exit of the last out of operation, before partial refusal of various sites of a chain. In particular, as a result of easing of fixture of devices brightness of a luminescence of lighting devices (can decrease in particular at the general grounding with other contour) or speed of rotation of the electromotor (for example, a drive of screen wipers or the fan of system of cooling). Thus refusal of one contour can cause infringement of functioning of the another which outwardly in any way have been not connected with failed. Pay attention that on many cars certain knots are connected among themselves by special tyres of grounding. Such tyres are used when there is no direct contact of metal parts of blocks in view of the equipment of support elastic rubber pillows and plugs (as, for example, in support of fastening of the power unit to the car chassis).