Execution order
1. A typical electrical circuit consists of electrical components, switches, relays, motors, fuses, fuse links, and the wires and connectors that connect all components to each other, the battery, and the vehicle's ground.
2. The cause of a fault can be found much faster if you determine which of the elements of the circuit are working properly. If several elements or circuits fail at once, the problem is likely a blown fuse or poor grounding, since one fuse often protects several circuits.
3. Electrical system problems are usually caused by simple issues such as corroded or loose contacts, a blown fuse, a blown fuse link, or a faulty relay. Visually inspect the condition of all fuses, wires, and connectors in the faulty circuit before checking other parts of the circuit.
4. The main devices required to detect a fault in a circuit are:
- tester or voltmeter (or 12V light bulb with connecting wires);
- test light with power source (or continuity tester);
- ohmmeter (for measuring resistance);
- battery;
- probes with wires;
- a test lead, preferably with a circuit breaker or fuse, that can be used to test wires or electrical components.
[The text is provided by the web resource: www.hyundaibook.ru]
5. To locate a poor connection or a short circuit (usually due to a poor or dirty connection or damaged insulation), the wires can be shaken by hand to see if the circuit breaks as the wire moves. This can help locate the point where the poor connection or short circuit occurs.
6. In addition to problems associated with a poor connection, an electrical circuit can have two other main faults - an open circuit or a short circuit.
7. An open circuit can be caused by a broken wire or a missing connection in the circuit that prevents current from flowing. An open circuit will cause a piece of electrical equipment to fail, but will not cause the fuse protecting that circuit to blow.
8. Short circuit faults are caused by a short in a circuit, which causes the current flowing in the circuit to flow through another circuit, most often to ground. A short circuit is usually caused by a break in the insulation, allowing the supply wire to touch either another wire or a grounded element, such as the body. The short circuit causes the fuse protecting the circuit to blow.
9. Before troubleshooting or making repairs to an electrical system, keep in mind that different types of wires have different colors.
10. To detect an open circuit, connect one of the test light probes to the negative battery terminal or vehicle ground.
11. Connect the second probe to a connection in the circuit being tested, preferably located as close to the battery or fuse as possible.
12. Apply voltage to the circuit. Remember that some circuits only apply voltage when the ignition key is turned to a certain position.
13. If voltage is present (as indicated by the indicator light or the voltmeter reading), that means the part of the circuit between the connection and the battery is good.
14. Continue checking the rest of the chain in the same manner.
15. When a point is found where there is no voltage, it means that the source of the fault lies between this point and the previous point where voltage was present. Most problems are due to a bad connection.
16. The negative terminal of the battery is connected to the vehicle chassis ground – the metal of the engine/gearbox and the car body – and most electrical systems are designed so that only one supply wire can enter the component, with the current returning through the metal of the car body. This means that the component mounting and the car body are part of the electrical circuit. Therefore, a poor or corroded mounting can cause a wide range of electrical system problems, from complete circuit failure to unreliable operation. For example, light bulbs may glow dimly (especially if another circuit using the same ground point is on), motors (such as windshield wiper motors or radiator fan) may run slowly, and turning on one circuit may affect the operation of another circuit. Note that many vehicles use grounding straps between various vehicle components, such as between the engine/gearbox and the car body, i.e. usually when there is no metal-to-metal contact between the elements due to the use of rubber mounts, etc.
17. To check for proper grounding, disconnect the battery and connect one of the ohmmeter probes to the vehicle's ground. Connect the other probe to the wire or ground point you want to check. The resistance registered by the ohmmeter should be zero, otherwise, check the connection as follows.
18. If you think the connection is not OK, disassemble the connection and clean the contact surface and the wire terminal or the surface of the grounded element to bare metal. Remove all dirt and corrosion, then use a knife to remove the paint layer to get a reliable metal-to-metal connection. Securely fix the connection when reassembling; when installing the wire terminal, use toothed washers between the terminal and the body. After connecting, apply a layer of Vaseline or silicone grease to the connection to prevent corrosion.
Fuses
Fuses are designed to break the circuit when the current reaches a certain value, in order to protect elements and wires that could be damaged by too much current. A sharp increase in current is usually caused by a fault in the circuit, most often a short circuit.
The designations of the circuits protected by the fuses are indicated on the fuse box cover.
Before removing a fuse, turn off the circuit in question (or the ignition), then pull the fuse out of the contacts. The wire should be visible inside the fuse; if the fuse is blown, the wire will be broken or melted.
Always use fuses of the correct rating. Never use a fuse of a different rating or replace it with anything else. Do not replace a fuse more than once without eliminating the source of the fault. The current protected by the fuse is indicated on the top of the fuse: note that fuses are colored differently for easy identification.
If a fuse blows immediately after replacement, do not replace it again until you have identified and corrected the cause of the fault. In most cases, the cause of the fault is a short circuit caused by poor insulation. If the fuse protects several circuits, try to find the circuit that is causing the fuse to blow, turning on each circuit in turn (if possible). Always keep a set of spare fuses of different ratings in the car. They should be secured to the base of the fuse box.