15.2. Detection of malfunctions in electric equipment system - the general description
The typical electric chain consists of an element of an electric equipment, switches, the relay, engines, the safety locks, burnt through crosspieces or automatic switches and wires and connections which connect all elements among themselves and connect them to the accumulator and (weight (the car. ' to simplify process of troubleshooting in the end of this chapter electric schemes of system of an electric equipment of the car are resulted.
Before the beginning of check of a faulty chain, in the beginning study the basic scheme of this chain to understand from what elements it consists. The malfunction source can be found faster if to define, what of elements of this chain work normally. If some elements or chains fail at once, the problem, possibly, consists in the fused safety lock or bad grounding as frequently one safety lock is responsible for some chains.
Problems with work of system of an electric equipment are usually caused by the simple reasons, such as the oxidised or unreliable contacts, the fused safety lock, the fused burnt through crosspiece or the faulty relay. Visually check up a condition of all safety locks, wires (if it is possible) and connections in a faulty chain before the beginning of check of other elements of this chain. If you are going to use instrumentations, use basic schemes to define, what connections are necessary for checking up for failure detection.
The basic devices necessary for search of malfunction in a chain of an electric equipment, are the voltmeter (or a bulb on 12 Volt with connecting wires), the device for check of integrity of chains, the accumulator with connecting wires and накидным a wire, it is desirable with the automatic switch which can be used for parallel connection to a chain. Before the beginning of search of malfunction with use of the control and measuring equipment, study basic schemes to define connection points.
Pressure check is necessary for spending, if the electric chain is faulty. Connect one of щупов a control bulb to the negative plug of the accumulator or (weight (the car. Connect the second щуп to connection in a checked chain, it is desirable located as it is possible more close to the accumulator or a safety lock. If the control bulb lights up, pressure is present: it means, that the chain part between connection and the accumulator is serviceable. Continue check of other part of a chain in the same way. When you will find a point where pressure is absent, it means, that the malfunction source lays between this point and last point where pressure was present. The majority of problems is caused by bad connection. The note. Do not forget, that pressure is present at some chains only if to turn a key in the ignition lock in certain position
Short circuit detection
One of methods of search of a point of short circuit consists 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 an electric equipment of this chain are switched off. In a chain there should not be a pressure. Move wires here and there and observe of a control bulb. If it lights up, means, somewhere in this area short-circuits one of wires, it is probable in that place where isolation was wiped. The same test can be spent on any other element of a chain, including the switch.
Check of reliability of grounding
Inspect reliability of grounding to check up reliability of connection of an element of an electric equipment to (weight (the car. Disconnect the accumulator and connect one of wires of the device for check of integrity of chains to "weight" 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, means, grounding is perfectly in order.
Check of integrity of a chain
Check of integrity of a chain is necessary to define, whether is not present in a rupture chain. Disconnect pressure from a chain and check up a chain on integrity by means of a bulb with the connected power supply. Connect bulb wires to the chain ends (or by the positive end and "weight" of the car); if the control bulb lights up, in a chain there are no ruptures. If the bulb does not light up, means, somewhere in a chain there is a rupture. Precisely also it is possible to check up the switch, having connected a control bulb to switch plugs. After switch inclusion, the control bulb should light up.
Finding of not closed chain
Visually to find not closed chain happens difficult enough as the oxidised or bad connection of contacts frequently is difficult for noticing. Sometimes simply enough to move a wire of connection or a wire in a plait of wires to eliminate this malfunction. Unreliable work of elements of an electric equipment also is frequently caused by the oxidised or bad connection.
The malfunction finding in electric equipment system is represented enough simple operation if to understand, that work of system of an electric equipment is based that the current flows from the accumulator through wires, switches, the relay, safety locks and burnt through crosspieces to electric equipment elements (a bulb, the engine etc.) and on (weight) of the car, whence it arrives back in the accumulator. Any malfunction in electric equipment system represents a hindrance in a current of a current from - or to the accumulator.