Flasher relay has two or three pins, unlike the standard relays that have four to five pins. In a two-pin flasher, one pin is connected to power and the other to the light circuit. While three-pin flasher with an addition pin that would be connected to an indicator light that lets the user know flasher is on. Not all flashers relay actually operate as a relay, some act more like a circuit breaker. But they are still group as relays. Most flasher relays are thermally controlled like a circuit breaker.
Current flows through the coil of the flasher relay create enough heat. This heat causes the contacts inside the relay to deflect causing the contacts to open and stop the current flow. Once enough heat has dispelled, the contacts will return to their original position and a current will flow again.
Well, numbers of light connected to a thermal flasher will determine its output performance. Electromechanical flashers work with a circuit board that contains a capacitor, a couple of diodes, and a coil to create the same flash pattern as a standard flasher. These types of flasher relays are capable of handling higher loads with improved performance over thermal flashers. The numbers of light connected to these types of flashers have less effect on its output. Wig-wag types of flasher are also known as alternating flashers that uses a solid-state flash circuit.
This circuit helps to alternate between two separate lamp circuits. Skirted types of relays have an extended skirt around its bottom to seal around a socket. This avoids water and contaminants from entering the relay contacts.
These relays are often used in exposed areas of automotive. Read more: Understanding the working of electronic ignition system. The working of relays is less complex and can be easily understood.
This spring holds the switch in position until a current pass through the coil. The coil then generates a magnetic field that moves the switch that turns on and off. In the above diagram, there is a pinout of a typical 12V relay. These pins are numbered; 85 and 86 are the coil pin while 30, 87, and 87a are the switch pins. That is, if the coil is not activated, 30 will always be connected to 87a which is when the switch is OFF. But if the current is applied to the coil, 30 will then contact pin Well, depending on how you want a relay to work, you can set 87 and 87a to be either open or closed.
If your equipment requires a closed relay, you will want to wire it to 87a, it can also be reversed if you want a Normally open relay. It comes in many different types, desig ns, and sizes. Each relay has its application. Here our focus will be on the electro-mechanical type relay because it is widely used in automotive applications. Relays are used for momentary input, time base function, and doing alternative work like flushing alternative left or right lights.
Some examples of logic function in a car, interior lights, time delay operation of wiper blades. Since a mechanical contact A movable contact that makes and breaks the connection and an electrical coil which produces magnetism to attract movable contact is used to do their job that is why a car relay is called in both ways Electromechanical or electromagnetic Relay. An electro-mechanical relay comes in many shapes and sizes.
All are used for various demands of various applications. Here are some most common types of the electro-mechanical relay. A Timer relay is operated for a while before turning off. A good example is the heated rear window, where the relay is activated for a while then is turned off. A Fuel injection relay electronically operates fuel injectors in the petrol engine.
Almost all cars have a flasher relay. They are used for indicators and hazard warning lights. The Diesel engine uses a relay to heat the glow plug for some time. Relays come in different voltage ratings 5 volts, 6 volts, 12 volts, and 24 volts. It also comes in different sizes and designs.
These kinds of relays are also very common in the car. Electromagnetic relays are a traditional type of relays used in an automotive vehicle. Most of the relays are volt and some cars have volt relays. Here are the most common types of relays used in cars. Four-pin relays are the most common type of car relays.
It is the most widely used relay in an automotive vehicle. Most automotive relays you see in a car are 4 pin relays. In four pin relay, there are two circuits primary and secondary circuits. Each circuit has two wires. Let me further elaborate. The primary circuit is also called a coil circuit consist of terminals 85 and Similarly, the secondary circuit also called high amperage or load circuit consist of terminal 30 and In the coil circuit terminal, 85 is usually connected to a negative power, and terminal 86 is connected to a positive power source.
But be cautious, here is the risky point. If you connect it the other way, you are more likely to harm the device, especially when it is connected to a sensor or transistor. Actually, from the coil circuit when the current is removed a voltage spike is produced, which can harm the electronic devices.
Therefore a diode is fitted across the coil circuit to dump the electrical spikes. In the secondary circuit, one wire which comes out of the relay is called terminal It means when the relay is activated, the power goes in through terminal 30 and exits through terminal On the other hand, when the relay is de-energized, the secondary circuit breaks and disconnects the current flow.
Usually, a headlight system uses a 4 pin relay. A five-pin relay is a type of car relay, which has five pins. It is mainly used for circuits that need power when the relay is not activated. A five-pin relay is mainly used for circuits that do not need power when the relay is active.
It comes in various design and pin arrangements but, the main function is the same. A five-pin relay works the same way as a four-pin relay. But, there is one extra pin added to the high amperage circuit of the five-pin relay that is called 87a. When the relay is not energized the movable contact which is common terminal 30, rests at 87a terminal position.
But, when the relay is energized the movable contact terminal 30, disconnect from terminal 87a, and moves to terminal By energizing and de-energizing the relay, the movable contact of the high amperage circuit shifts back and forth to 87 to 87a terminals.
Due to these changing features, the five-pin relay is also called Changeover Relay. When there is no voltage applied to the coil circuit, one circuit of high amperage terminal 30 to 87a terminal is in touch with each other and can receive current, but the other terminal Terminal 30 and 87 does not receive current.
While the coil circuit gets energized, the second circuit of high amperage Terminal 30 and 87 receives current. A five-pin relay is usually used in headlight operation where the relay can switch between two circuits to activate full beam and low beam as required. I am explaining the three-pin relay in the last because when you have a better understanding of the four and five-pin relay, then it will be easy for you to understand a three-pin relay.
A three-pin relay is a type of car relay, which has three pins. It works on the same principle as a four and five-pin relay. Its basic construction and operations are the same as of four and five-pin relay.
In a four-pin relay, four wires come out of the relay. Two wires for the coil circuit 85 and 86 Terminals and the remaining two wires are for the high amperage circuit 30 and 87 Terminals. Both wires Terminal 86 and 30 are joined together and come out as a single wire from the relay. And other two wires 85 terminal of coil circuit and 87 terminal of high amperage circuit also come out separately. Always connect the hot power source to the joint terminal Terminal 86 and And the other two terminals, terminal 85 should be given the ground power source, and the 87 will go-to accessory.
These relays were used in older cars especially for horns. Nowadays these three-pin relays rarely come in a car for horn. Some relays are marked on the case for identification purposes. A relay is marked up with 6, 12, and 24 volts.
Remember this current rating is for a high amperage circuit. The numbers 85, 86, 30, 87, and 87a are marked on the plastic case of the relay along with circuit schematics.
The purpose of a relay is to increase the efficiency of a component by providing the proper amount of current. Relay also allows the component to function at a peak performance level. Some circuits take a long distance to operate like a car headlamp or air conditioning system.
It takes a few meter wire distances to operate from the dashboard to the engine compartment. And also we know that the longer the wire distance, the more resistance it has.
Hence, causes a high voltage drop and the component will not function in a fully excellent way. So, by using a relay we reduce the voltage drop. The function of the relay is also to control multiple circuits with one relay. A single relay trigger, will activate one or more higher current circuits.
These circuits do multiple functions at the same time without using a bunch of relays and wires. A good example is a car control locking system. A single trigger result in all door locks locking or unlocking simultaneously. One great use of a relay is to handle the high current load by using a low current load.
Some accessories need too much current which exceeds the capacity of the wire, causes burned to the wire. In this case, if you use a relay, you will protect the circuit from overloading or overstressing the wire. Also, a good benefit of using a relay is that you will not need high current rated cables. For example, high output headlamp requires a high amount of current which overloads the wire capacity.
By using a relay we switch high current circuits using a lower current circuit. A normal relay can handle current up to 40 amp. Another good function of using a relay is, it allows you to use a separate and proper fuse for each circuit. This voltage is several hundred volts, b ut with very low amp current, and will cause arching on switch contacts or can damage sensitive electric devices. A diode is installed across the coil in a reverse-biased position and prevent the damage by absorbing the high voltage spikes and dissipate them.
Thus, no current will flow through the diode, and electrical components are protected from damages. Sometimes a resistor is used in place of a diode. The function of the resistor in a relay is the same as in a diode to dissipate high voltage spikes. But, here is a problem, this configuration is not as effective as a diode in stopping high voltage spikes. A little bit of voltage can leak through a resistor and can cause electrical damage.
But, here is also a piece of good news for you. The resistor has one advantage over the diode. It is not sensitive to polarity and you can connect any power source Ground or Hot to any terminal of the coil circuit Terminal 85 or In this tutorial, I will show you step by step procedure of how to test an automotive relay. One thing you need to know about testing a relay is that the basic procedure of testing every relay in a car is the same.
Whether that is a fuel pump relay, Starter motor relay , Car Air Conditioner relay, Headlight relay, radiator fan relay, or horn relay. I will take the horn relay as a sample to make you understand in a better way. Suppose your car horn does not work.
Here I will show you in seven steps how to figure out the fault when the horn does not work. Before checking the relay, It is wise to check the horn fuse. The fuse schematic is usually printed on the inside of the fuse box cover or sometimes outside of the cover. First of all, check the relay location.
Fuse box comes in many different locations. It comes under the hood, under the dashboard, or side kick panel. But usually, a car horn relay comes under the hood fuse box. Once a relay is figured out, have a helper beep the horn and touch the relay if it makes a clicking sound. If so the relay is working fine. In this case, the horn might be faulty or has a wiring issue. If the relay does not make a clicking sound, then proceed to the next step.
Now It is time to remove the relay from the fuse box for inspection purposes. Smoothly grasp and pull the relay upward by hands while slightly wiggling the relay for gentle extraction. Check relay pin connector and fuse box female connector of the related relay.
Make sure the connectors are clean. Sometimes overheating prevents proper current flow in a circuit. Find out which terminal belongs coil and load circuit. Some relays have a diagram printed on the case itself to identify pin terminals. Before you test the relay It is good to check the horn.
Make sure you have a good working horn. To test the horn, take a jumper wire, strip both ends of wire insulation exposing copper. The open or closed position of the relay depends on its design and controlled by whether the relay is at rest or energised.
A normally open relay, NO , at rest has a broken contact - it's open. The reverse is true for a normally closed, NC , relay. A normally closed relay at rest has a closed contact. Typically the relay is switched manually using push or toggle switch - an everyday example of this is the car ignition switch used to start the engine. A changeover relay is built with two circuits instead of one and five pins rather than four. Instead of making and breaking a single high voltage circuit it alternates the closing and opening of two circuits - 'changing over' which circuit is open or closed.
A typical example of a change-over relay in use can be seen in the operation of vehicle headlights. The relay can switch between circuits to activate the full beam or dipped beam as required. Another everyday example is the car air-conditioning system. One or the other will be running and never both at the same time. Changeover relays are sometimes referred to as Single Pole Double Throw relays. The terminals of a relay are numbered using an identification system known as DIN This system was developed in the German automotive industry and has since been adopted across the world as the standard method for labelling and identifying electrical terminals.
The table below shows the codes used in automotive relays. Some automotive relays are designed with diodes or resistors built in. These devices help suppress coil voltage spikes and protect the electronic circuit. When the voltage is removed and a relay is denergised the magnetic field collapses. This can result in a voltage surge in the opposite direction.
These low current surges can have significantly high voltages, often up to volts. To prevent the damage of sensitive upstream electronic circuitry a diode can be installed across the coil. The diode absorbs and dissipates the momentary voltage spike and protects upstream damage. Resistors can be employed to provide protection similar to a diode in the previous example. They too can absorb voltage spikes which result from a sudden magnetic field collapse. A resistor however allows a small current to flow and is not as effective as a diode in absorbing a voltage surge.
The advantage a resistor holds over a diode is that it is not sensitive to polarity and the 12v can be connected to either the 85 or 86 terminal, as per DIN A micro relay is a smaller version of the more popular standard relay and are used when space is at a premium. Note, a standard relay is also sometimes referred to as a 'Mini Relay'. Micro relays are more compact than the standard size and are an ideal choice when you need to save space - for example in an ATM fuse box set up with mini fuses.
They have a smaller rectangular shape compared to the square cubed shape of the standard relay. Micro automotive relays use a different terminal number identification system compared to standard mini relays.
See the list below for micro relay terminal numbering:. A typical car can contain up to twenty automotive relays and they can be located throughout the vehicle. However common locations for their installation are in the engine compartment behind the kick panels and underneath the dash.
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