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How to test Electrical Circuits

Here you can get Electrical Circuits. Here we provide how to test Electrical Circuits, symbols used in wiring diagrams, types and Problems.

If there is trouble without an obvious cause in any electrical component, test the circuit to find the cause.

Cars and light trucks have extensive electrical systems with lots of wiring and hundreds of circuits. An electrical circuit is basically a route or path through which electrons flow. An electrical circuit must form a complete loop so the current will continue to flow. The electrons need a return path back to their source (the battery or alternator) otherwise they have no place to go.

Electrical Circuits

Cars and lightweight trucks have extensive electrical systems with many wiring and hundreds of circuits. An electrical circuit is essentially a route or path through which electrons flow. An circuit must form an entire loop therefore the current will still flow. The electrons need a return path back to their source (the battery or alternator) otherwise they need no place to go.

A typical car lighting circuit

A circuit tester is a useful and inexpensive tool for making electrical tests. Checking a simple circuit is straightforward – the lighting circuits are among the simpler ones – but the electrical wiring in a car contains many interlinking and branching circuits, which bring complications.

All car wiring is color-coded; unfortunately there are no national or international standards for colors. Color codes for individual cars can be found in wiring diagrams , in the car handbook or in a service manual.

Some symbols used in wiring diagrams

Study these diagrams in order that you can find short cuts which prevent having to see an entire circuit. For example, if you recognize that the power for a suspect circuit comes from the ignition switch, and if other items fed from that switch are working, there are often no fault between the battery and the ignition. So you’ll save time by starting at the switch.

How to use a circuit tester

Connect the tester clip to the negative terminal of the battery and touch the probe to the positive one. If the tester lamp doesn’t light, the battery is dead (or the bulb within the tester has blown). If it lights, try again with the clip earthed to the car body: if the lamp fails to light, the battery negative terminal isn’t earthed properly.

Earth the clip near the switch of the circuit being tested and touch the probe to the ‘live’ (battery) side of the switch. If the lamp doesn’t light, the wiring between the battery and therefore the switch is faulty, or a fuse has blown.

Types of Electrical Circuits

There are essentially two types of automotive electrical circuits:

A series circuit is one during which all the circuit elements are connected end-to-end in chain-like fashion. the current has just one path to follow therefore the amount of current passing through it’ll be an equivalent throughout. the entire resistance during a circuit is adequate to the sum of the individual resistances within each circuit element. If one element during a series circuit goes bad, continuity is broken and the entire circuit goes dead because the current cannot complete its journey through the circuit.

A parallel circuit is one during which circuit elements are connected next to or parallel to at least one another. This creates multiple branches or pathways through which current can flow. The resistance in any given branch will determine the drop and current flow through that branch which branch alone. one of the advantages of a parallel circuit is that the varied segments or pathways of the circuit can operate independently of 1 another. If one element goes open (breaks continuity), it won’t disrupt the function of the opposite .

Some circuits combines elements of both a series and parallel circuit. These would be called a series-parallel electrical circuit. during this type of circuit, a part of the circuit may need loads serial while in another part the loads would be parallel.

Troubleshooting automotive electrical circuits often requires measuring volts, amps or ohms. These are three basic units of measurement that are used to describe what goes on inside an electrical circuit.

Common Problems in Automotive Electrical Circuits

Shorts are a type of fault that can occur if the present traveling through an circuit doesn’t pass through the component powered by the circuit, but finds another path to ground. this will happen if a wire rubs against a pointy edge and shorts to ground, or the insulation on adjacent wires rubs through or is damaged allowing current in one wire to leap to an adjacent wire. a brief may result in a runaway current because of reduced resistance within the circuit. this will cause a wire to rapidly overheat, possibly melting or burning the insulation around it and starting an electrical fire. a brief will usually cause the circuit fuse to blow.

Note: If a circuit has a blown fuse and a new fuse blows as soon as you replace it, the circuit most likely has a short.

Shorts most often occur where wiring rubs against a pointy metal edge, as where wiring passes through a bulkhead, the firewall between the engine compartment and passenger compartment, or door or other body cavity. Rubber grommets are typically wont to protect the wiring in places where the wiring passes through metal panels. But if the grommet is broken or missing, the wiring my rub against a pointy edge and short out.

Shorts also can occur between adjacent wiring if the insulation round the wires is broken or cracked. Insulation can become brittle with age and should crack or flake off the wiring, allowing the bare metal underneath to form contact with adjacent wires or the body.

Intermittent shorts can occur when wires make intermittent contact as a results of temperature changes that cause metal to expand and contract, or as a results of vibration. Finding intermittent shorts are often difficult because the matter comes and goes. Wiggling and shaking wires, or blowing hot air on them with a hot air gun could also be necessary to simulate the conditions that cause the short to occur.

Shorts are often repaired by wrapping exposed or damaged wiring with electrical tape, or replacing the damaged wiring.

Opens are another type of fault which will occur in automotive electrical circuits. An open is simply what the name implies: an open within the wiring that stops the flow of current and kills the circuit. An open won’t blow a fuse, but it’ll prevent the circuit from functioning. An open may occur if a wire breaks, a wiring connector is loose or unplugged, or severe corrosion inside an electrical connector has created so much resistance that current cannot flow through the circuit.

Opens also can occur in electronic circuits if micro cracks form in soldered connections or on printed circuit boards. The circuit may pass current normally when cold, but because it heats up and expands, the micro cracks may open up causing an intermittent open.

Overloads are a condition which will occur during a circuit when an electrical motor or other device experiences operating conditions that cause it to draw more current than normal. An example would be a temporary overload within the windshield wiper motor circuit if the wipers become jammed with ice or heavy snow. An overload may cause the circuit fuse to blow.

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