General description
A typical electrical circuit consists of an electrical element, switches, relays, fuse motors, circuit breakers, wires, and connectors that connect the electrical element to the battery and body. To assist in troubleshooting the electrical system, diagrams of the vehicle's electrical system are provided at the end of this manual.
Before attempting to determine the source of a fault, first study the relevant circuit diagram to get an idea of the elements installed in this circuit. The circle of possible sources of malfunction can be narrowed down by checking the functioning of other elements included in this circuit. If several elements or circuits fail at the same time, then the problem is obviously a fuse common to these circuits or elements, or contact with the body.
Electrical problems are usually caused by simple causes such as loose or corroded connectors, no contact with the body, blown fuses, a blown jumper or a bad relay. Visually check the condition of all fuses, wires and connectors in the failed circuit before proceeding to check the rest of the elements. Use the wiring diagrams to determine which end clamps need to be checked to find the source of the problem.
The main tools needed to locate the source of the fault are a tester or a voltmeter (a 12 volt bulb and a pair of wires with probes at the ends, can also be used for some tests); ohmmeter; a battery and a set of wires with probes, a cap puncture, preferably with an automatic switch or fuse, which is used to bypass the tested wires or elements.
To detect the cause of unreliable operation of any of the elements (usually due to poor connection or dirty contacts, or damaged insulation), you can check by shaking the wires. It is necessary to shake the wire by hand to check if the fault appears when the wire is moved. With this method, you can narrow the circle of possible sources of malfunction to any wire.
Along with problems due to poor wiring, two main types of faults can occur in an electrical system - an open circuit or a short circuit.
Open circuit problems are caused by an open circuit in electrical equipment that interrupts the flow of current. An open circuit will cause the piece of electrical equipment to shut down.
Short circuit problems are caused by short circuiting a section of a circuit, causing current to leak from another circuit, usually directly to the body. A short circuit is usually caused by a break in the insulation of the wires, allowing the wire to touch another wire or some grounded item, such as the body. A short circuit will usually blow the corresponding fuse.
Open circuit detection
To test for continuity, connect a circuit tester or negative voltmeter probe to the negative battery terminal or ground.
Connect the second probe to the connection in the circuit under test, preferably closest to the battery or fuse. In this case, this section of the circuit must be energized by the battery, unless the battery connector is conducting current or the fuse has not blown (at the same time, do not forget that some electrical circuits are switched on only when the key in the ignition switch is turned to a certain position).
Turn on the circuit, then connect the tester probe to the connection closest to the circuit breaker on the side of the item being tested. If voltage is present (as evidenced by a control light or voltmeter readings), this means that the value section between the corresponding connection and the switch has no gaps. Continue checking the target in the same way, and after finding a section where there is no voltage, this means that an open circuit occurred between this point and the point of the previous test, which had voltage. Most open circuit problems are caused by a broken or loose connector.
Short circuit source detection
To locate the source of the short circuit, first disconnect the load elements of the circuit (circuit load elements are elements that consume electrical current, such as light bulbs, electric motors, heating elements, etc.).
Remove the appropriate fuse and connect the tester or voltmeter leads to the fuse terminals.
Turn on the power in the circuit, while not forgetting that some circuits of electrical equipment are turned on only when the key in the ignition switch is turned to a certain position. If voltage is present (as evidenced by a control light or voltmeter readings), this means that there is a short circuit in the circuit.
If there is no voltage during the test, but the fuse still blows when that circuit load is connected, this indicates a failure of the load element.
Bad ground detection
The negative battery terminal is connected to "mass" - to the metal of the body, engine or gearbox, while many elements of electrical equipment are connected in such a way that only a positive wire is suitable for them, while the current returns to the battery through the metal of the body. This means that the electrical component attachment and the bodywork are part of the electrical circuit. As a consequence, a bad or corroded fastener can cause the element to fail or result in unstable or poor performance. In particular, light bulbs can burn dimly (especially if at the ground point of this bulb, the grounding of some other piece of electrical equipment that is still switched on is carried out), electric motors can run slowly, and the operation of one circuit may have an imperceptible effect on the operation of another circuit. Keep in mind that many vehicles use ground wires between certain parts such as the engine/transmission and the body where there is no direct metal to metal contact due to soft rubber mounts or a layer of paint.
To check the reliability of the grounding of the element, it is necessary to disconnect the battery and connect one of the ohmmeter probes to a reliably grounded element. Connect another probe to the wire or body connection to be tested. The resistance shown by the ohmmeter should be zero; if not, check the connection as follows.
If you suspect that there is no ground, disassemble the connection and clean the body area and wire terminal (or element ground surface) to bare metal. Carefully remove all traces of dirt, then use a knife to remove all paint so. to ensure reliable contact between two metal surfaces. When assembling, securely tighten the connector fastener; When connecting the wire terminal, place a serrated washer between the terminal and the body surface to ensure a secure connection. When connecting, prevent future corrosion by applying a coat of Vaseline or silicone grease.
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