Circuit fault detection
A typical electrical circuit consists of an electrical element, switches, relays, motors, fuses, circuit breakers, wires and connectors that connect the electrical element to the battery and body. To assist in troubleshooting the electrical system, the manual provides wiring diagrams for the vehicle.
Before attempting to determine the source of a malfunction, study the appropriate electrical circuit diagram to get an idea of \u200b\u200bthe elements of this circuit. The number of possible sources of malfunction can be reduced by checking the operation of other elements included in this circuit. If several elements or circuits fail at the same time, the fuse common to these circuits or elements may be defective, or the connection to the body is broken - «weight».
The causes of the malfunction are loose or oxidized connectors, poor contact with the body, burned out circuit breakers or faulty relays. 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 the end clamps that need to be checked to find the source of the problem.
The main instruments needed to locate the source of a malfunction are a tester or voltmeter, a 12 V test lamp, an ohmmeter, a battery and a set of wires with probes, a captive puncture, preferably with a circuit breaker or fuse, which is used to bypass the tested wires or elements.
In addition to a bad wire connection, there are two main types of faults that can occur in an electrical system - an open circuit or a short circuit.
The circuit opens as a result of an open circuit in the electrical equipment, which interrupts the current and causes the electrical equipment to turn off.
To test continuity, connect a circuit tester or voltmeter, one lead to the negative battery terminal or ground, and the other to a terminal in the circuit under test, preferably one that is closest to the battery or fuse. In this case, the tested section of the circuit must be energized from the battery, except for the case when the connection to the battery does not conduct current or the fuse is blown (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 lead to the connection closest to the circuit breaker on the side of the item being tested.
If there is tension (as evidenced by a control lamp or voltmeter readings), which means that there are no breaks in the section of the circuit between the corresponding connection and the switch.
If a section is found where there is no voltage, then an open circuit occurred between this point and the point of the previous test, which had voltage. An open circuit is caused by a damaged or loose connector.
To find the source of a short circuit, disconnect electrical consumers - lamps, 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 there is voltage in the circuit (as evidenced by a control lamp or voltmeter readings), which means that a short circuit has occurred in it.
If there is no voltage during the test, and the fuse still blows when the same load is connected, the load element has failed.
The negative terminal of the battery is connected to «mass» – to a body, the engine or a transmission. An insecure or oxidized fastening may cause the element to fail or malfunction. Do not forget that many cars use «massive» wires between certain elements, such as the engine/transmission, and the body, i.e. in places where there is no direct contact between metal elements 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 leads to a reliably grounded element. Connect the other lead 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 the reliability of contact with «weight», disassemble the connection, remove dirt and clean the contacts. When reassembling, tighten the connector retainer by applying a coat of petroleum jelly or silicone grease to prevent corrosion.
General recommendations
Before removing electrical components or disconnecting electrical connectors, disconnect the battery, having previously found out if you have a radio activation code.
Turn off the ignition and disconnect the wire «masses» from the battery.
After installing the electrical equipment or electrical connectors, connect the wire «masses» to the battery.
Turn on radio and enter the code into it.
Raise the windows with the power windows up to the stop. Then press all power window switches again for at least 1 second to the closed position to activate the power window control unit.
Set the time on the clock.
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