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Detection of open circuit

Before trying to determine the source of the fault, first study the corresponding scheme of an electric equipment for representation reception about the elements established in this chain. The range of possible sources of malfunction can be narrowed if to check up functioning of other elements entering into the given chain. If some elements or chains emasculated fail simultaneously, the problem is obviously to fuse common to these circuits or elements, or contact with a body.

Electric problems are usually caused by the simple reasons, such as the weakened or rusted sockets, absence of contact with the body, blown fuses, melts smiling through crosspiece or the faulty relay. Visually check the condition of all safety locks, wires and sockets in the failed chain before to start check of other elements. Use the diagrams to determine which of the terminal clamps must be checked to detect the source of the fault.

The basic tools necessary for detection of a source of malfunction are the tester or voltmeter (a bulb on 12 volt and the pair of wires with probes at the ends can also be used to carry out some checks); ohmmeter; the battery and a set of wires with probes, puncture the cap, preferably with a circuit breaker or fuse, which is used for detour of checked wires or elements.

To find the cause unreliable operation of any of the elements (usually because of a bad connection or pollution of contacts, or damaged insulation), it is possible to inspect stirring of wires. It is necessary to shake a wire by hand to check to see whether the malfunction at wire movement. So metol can narrow down the possible sources of malfunction to any wire.

Along with problems due to poor wiring, two basic types of malfunctions can occur in the electrical system - Open circuit or short circuit.

Problems appear as an open circuit as a result of an open circuit of electrical equipment, which interrupts the flow of current. Open circuit element will cause disabling of electrical equipment.

Problems with short circuit caused by a short circuit part of the circuit, which leads to leakage current from the other chain, usually directly on the body. Short circuit is usually caused by rupture of isolation of wires that allows a wire to concern other wire or any earthed element, such as a body. Short circuit usually leads to burn out the appropriate fuse.

Detection of open circuit

To check the integrity of the chain connect the device for check of schemes or negative probe of the voltmeter to the negative terminal of the battery or grounded element.

Connect the other probe to connection in a checked chain, preferably closest to the battery and secure it Liu. In this case the circuit path to be energized from the accumulator if only the connection socket to the accumulator does not conduct current or blown fuse (thus do not forget that some chains electri tion applies only when you turn the key in the ignition lock in certain position).

Include a chain, then connect the probe tester to the connection nearest to the switch on the side of the circuit under test element.

If pressure is present (about what the control bulb testifies or voltmeter indications), it means that the site Exalt between corresponding connection and the switch has no ruptures.

Continue to check the circuit in the same way, and after the discovery of the site where there is no tension, it means that chain rupture has occurred between this point and the previous check on which there was tension. Most of the problems are caused by an open circuit broken or weakened socket.

Finding the source of the short circuit

For detection of a source of short-circuit in the beginning disconnect elements of loading of a chain (load circuit elements - elements that consume elec cue current, such as light bulbs, elektrodviga Teli, heating elements, and so on. D.).

Remove the appropriate fuse at the tester and connect the test leads or the voltmeter to safety lock plugs.

Turn on the power circuit, thus do not forget that some chains of an electric equipment join only at key turn in the ignition lock in certain position.

If pressure is present (about what the control bulb testifies or voltmeter indications), it means that the circuit is shorted.

If during the test voltage is not present, however the safety lock on the former fuses at connection of that loading of a chain, it testifies to the failure of an element of loading.

Detection of bad grounding

The negative battery terminal is connected to "weight" - the metal body of the motor or gearbox with many elements of electri tion connected in such a way that it is suitable only to the positive wire, while the current returns to the accumulator through body metal. This means that the electrical mounting element and the body are part of the electrical circuit. As a result, bad or rusted fastening can cause refusal of work of an element or lead to its unstable or bad work. In particular, bulbs can burn dim light (especially if in a point of grounding of this bulb is carried out grounding of any else included element of an electric equipment), electric motors can slowly work, and the work of one chain can have an imperceptible at first sight on work of other chain. Do not forget that on many cars grounding wires between some elements, such as the engine / transmission and body, that is, in those places where the pet direct contact between metal elements because of soft rubber fastenings or a paint layer.

To check the reliability of grounding of an element, you must disconnect the battery and connect one lead of an ohmmeter to reliably earthed element. Connect the other probe to the wire IPT connection with a body that should be checked. Shown by an ohmmeter resistance should be equal to zero; if not, check the connection as follows.

If you assume absence of grounding, disassemble connection and clear a site of a body and the wire plug (or the surface of the earth element) to pure metal. Carefully remove all traces of dirt, then use a knife remove all paint so that reliable contact of two metal surfaces. When assembling, tighten the connector mounting; When connecting the terminal wires, install the washer with the jagged edges between the plug and the surface of the body to ensure a reliable connection. When connected, prevent corrosion occurrence in the future, having put a layer of Vaseline or silicone grease.