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15.2. Detection of malfunctions in system of electric equipment - the general description

The typical electric chain consists of an element of electric equipment, switches, the relay, engines, safety locks, the burned-through crossing points or automatic switches and wires and connections which connect all elements among themselves and connect them to the accumulator and (to weight (the car.' To simplify process of troubleshooting in the end of this chapter electric circuits of system of electric equipment of the car are provided.
Before check of a faulty chain, study the schematic diagram of this chain in the beginning to understand of what elements it consists. The source of malfunction can be found quicker if to define what of elements of this chain work normally. If several elements or chains fail at once, the problem probably consists in the fused safety lock or bad grounding as often one safety lock is responsible for several chains.
Problems with work of system of electric equipment are usually caused by the simple reasons, such as the oxidized or unreliable contacts, the fused safety lock, the fused burned-through crossing point or the faulty relay. Visually check a condition of all safety locks, wires (if it is possible) and connections in a faulty chain before check of other elements of this chain. If you are going to use instrumentations, use schematic diagrams to define what connections need to be checked for failure detection.
The main devices necessary for search of malfunction in electric equipment chain, are the voltmeter (or a bulb on 12 Volts with connecting wires), the device for check of integrity of chains, the accumulator with connecting wires and a cap wire, it is desirable with the automatic switch which can be used for parallel connection to a chain. Before search of malfunction with use of the control and measuring equipment, study schematic diagrams to define connection points.
Check of tension
An inspection of tension needs to be carried out if the electric chain is faulty. Connect one of probes of a control bulb to the negative plug of the accumulator or (to weight (the car. Connect the second probe to connection in the checked chain, it is desirable located as it is possible closer to the accumulator or a safety lock. If the control bulb lights up, tension is present: it means that a part of a chain between connection and the accumulator is serviceable. Continue check of other part of a chain in the same way. When you find a point where tension is absent, it means that the source of malfunction lies between this point and the last point where tension was present. The majority of problems is caused by bad connection. Note. Do not forget that tension is only present at some chains if to turn a key in the ignition lock in a certain situation
Detection of short circuit
One of methods of search of a point of short circuit is in getting a safety lock and to connect a control bulb or the voltmeter to plugs of connection of a safety lock when all other elements of electric equipment of this chain are switched off. In a chain there should not be tension. Move wires here and there and watch a control bulb. If it lights up, so somewhere in this area short-circuits one of wires, it is probable in that place where isolation was wiped. The same test can be carried out on any other element of a chain, including the switch.
Check of reliability of grounding
Carry out an inspection of reliability of grounding to check reliability of connection of an element of electric equipment to (weight (the car. Disconnect the accumulator and connect one of device wires for check of integrity of chains to "mass" of the car. Connect the second wire to connection or a point of grounding which is subject to check. If the control bulb lights up, so grounding as it should be.
Check of integrity of a chain
Check of integrity of a chain is necessary to define whether is not present in a gap chain. Disconnect tension from a chain and check a chain for integrity by means of a bulb with the connected power supply. Connect bulb wires to the ends of a chain (or by the positive end and "mass" of the car); if the control bulb lights up, in a chain there are no gaps. If the bulb does not light up, so somewhere in a chain there is a gap. In the same way it is possible to check the switch, having connected a control bulb to switch plugs. After turning on of the switch, the control bulb has to light up.
Finding of not closed chain
To visually find not closed chain happens rather difficult as it is often difficult to notice the oxidized or bad connection of contacts. It is sometimes rather simple to move a wire of connection or a wire in a plait of wires to eliminate this malfunction. Unreliable work of elements of electric equipment is also often caused by the oxidized or bad connection.
Finding of malfunction in system of electric equipment is represented rather simple operation if to understand that work of system of electric equipment is based that current flows from the accumulator through wires, switches, the relay, safety locks and the burned-through crossing points to electric equipment elements (a bulb, the engine, etc.) and on (mass) of the car from where it comes back to the accumulator. Any malfunction in system of electric equipment represents a hindrance during current from - or to the accumulator.