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 an electric equipment in a management schemes of an electric equipment
of the car are resulted
Before to try to define a malfunction source, study the corresponding scheme of an electric equipment for representation reception about elements in this chain. The number of possible sources of malfunction can be reduced if to check up work of other elements entering into the given chain. If some elements or chains fail simultaneously, probably, 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 oxidised sockets, infringement of contact to a body, the fused safety locks or faulty relays. Visually check up a condition of all safety locks, wires and sockets in the failed chain before to start check of other elements. Use schemes of an electric equipment for
definition of places of possible malfunctions which are necessary for checking up for detection of a source of malfunction.
The basic 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, накидной a puncture, it is desirable with the automatic switch or a safety lock which is used for detour of checked wires or elements.
Except bad connection of wires in electric equipment system two more cores of type of malfunctions — the opened chain or short circuit are possible.
The chain is disconnected as a result of breakage in an electric equipment chain that interrupts a current, causing switching-off of an element of an electric equipment.
For check of an integrity of a chain connect the device for check 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 nearest to the storage battery or a safety lock. Thus checked site of a chain should be energised from the storage battery, except for a case when the connection socket to the battery does not spend a current or has fused a safety lock (do not forget that some chains of an electric equipment join only at key turn in the ignition lock in certain position).
Include a chain, then connect щуп a tester to the connection nearest to the switch of a chain on the party of the checked element.
If there is a pressure (to what fire of a control lamp or the voltmeter indication testifies), means, in a chain site between corresponding connection and the switch there are no ruptures.
If the site on which there is no pressure is found out, means, chain breakage has occurred between this point and a point of the previous check on which there was a pressure. Chain breakage is caused by the damaged or weakened socket.
Possible sources of short circuit following consumers of the electric power can be: lamps, electric motors, heating elements, etc.
Remove a 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 an electric equipment join only at key turn in the ignition lock in certain position.
If in a chain there is a pressure, 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 oxidised fastening can lead to refusal of an element or infringement 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 up. Resistance shown by an ohmmeter should be equal to zero if is not present check up connection as follows: if raises the doubts reliability of contact to "weight" disassemble connection, remove pollution and smooth out contacts. At assemblage tighten socket fastening, having put a layer of technical vaseline or silicone greasing for corrosion prevention.