Turn Signal Relay: Why You Need To Take It Seriously

Turn Signal Relay: Why You Need To Take It Seriously

The turn signal relay or the hazard lights found in all vehicles are controlled by a flasher. This flasher is commonly referred to as the relay. The flasher is just an electrical component that operates as a switch to enable the lights to flash on and off. They are produced in different shapes sizes and designs depending on the specific model of your car.

In the process that current is applied into the relay, the circuit inside cuts on and off resulting in the clicking sound we normally hear that is associated with the relay. This also enables the flashing of the turn signal relay or the hazard light.

These are the simplest components of a car both in design and operation. Flashers are an essential device on your car. It enables smooth driving and effective communication with other motorists on the road. Without it, your safety and that of other motorists can be compromised. There will not be effective communication with other motorists on the road.

It is obvious that when these components fail, they exhibit certain symptoms that are enough to alert you to take the necessary steps to fix them immediately. Troubleshooting turn signal relay isn’t such a difficult task.

A bad turn signal relay may exhibit; rapid blinking, lighting on continuously, or not lighting up at all. The good thing is that this failure often points out two things; a bad flasher or a blown bulb.

When the turn relay signal blinks so fast it could signal a loose bulb. If it does not blink at all, a replacement may be necessary. The turn signal relay is easy to replace, and it is not that expensive to fix.

Contents of this article entail;

What Is A Turn Signal Relay

A turn signal relay is an electrical system that helps a motorist to indicate to other motorists on the road of a car’s intentions to avoid abrupt unexpected turns that can lead to collisions. The motorist can indicate to other motorists early enough on the direction the car will take a turn towards.

For this component to work effectively, there has to be an electrical power supply that enables the turn signal relay to blink. The blinking is enabled by a component called the signal relay. Turn signal relays are controlled by a flasher. It is this flasher that is also called a relay.

The flasher also forms part of this electrical system. It helps to control when the system flashes on and off. The turn signal relay comes in different shapes sizes and designs depending on the needs of your car.

Types Of Turn Signal Relay

There are four different types of turn signal relays. They range from the traditional ones that were commonly used in older models of cars to the more sophisticated modern types used in modern cars.


Mechanical turn signal relays are mechanical switches that switch power to turn the turn signal bulb using a bimetallic strip metal and a heater they are mainly used in older models of cars. They mainly rely on the heater and the bimetallic strip to operate.


They are mainly found in modern types of cars without mechanical signal parts. The flasher usually measures the amount of current that flows to the turn signal relay bulb. In case the current drawn falls in a given expected range, a timing mechanism, and a transistor turn power on and off to light the signal bulb.

Turn Signal Relay

Electronic flashers do produce an audible clicking sound that resembles one of older mechanical units to remind the driver that the turn signal is operating.


A thermal turn signal relay is an improvised version of the mechanical relay signal. The bimetallic strip contains an electrical contact and is slightly curved in shape when not on.

When a driver operates this type of turn signal, power flows through the heater in the turn signal, and then through the turn signal bulb.

Since the heater is a high resistance wire, the current that flows to the bulb is not enough to light them. The current that flows through the heater is enough to heat the bimetallic strip once the bimetallic strip is heated, it changes shape and flattens out.

This is when the contact touch and full current flows to turn the signal bulbs causing them to light up.

Once lit, the current then bypasses the heater, and it shuts off. This causes the bimetallic strip to cool and turn back to its curved shape. This snapping by the bimetallic strip is what causes the clicking sound.

Solid State

The solid-state turn signal relay is also found in most modern cars. They make use of the digital technology that is activated using computer chips.

When the activation of the turn signal relay takes place with a solid-state flasher, the amount of current produced flows through a solid-state timing chip causing it to activate, interrupt, and reinstate flow to the turn signal bulbs using a transistor.

This flashing mimics that which is produced by the thermal flashers. They also mimic the sound produced by thermal flashers to give an audible signal to the driver that the turn signal relay is operating.

How A Turn Signal Relay Works

The turn signal requires electrical power to enable the lighting of the signal bulbs. This system is protected by a fuse in the power junction box so that it is not affected in any case there is an electrical fault in the car.,

The power that lights up the turn signal relay bulbs originates from the junction box and flows through the fuse. The flasher unit is then plugged into the fuse. When the turn signal relay lights illuminate, they do so through flashes in an arithmetic pattern to show the other motorists of your intention.

This is achieved by routing the power to the turn signal through a flasher or a module that can send pulses of energy to enable the lighting in flashes instead of a steady stream.

As the driver completes the turn, and the steering wheel is released back to the central position, a cam on the steering column catches on the turn signal lever and cancels the turn signal operation.

However, in case the cancel cam is broken, the signal will not turn off on its own, you will have to turn the signal off by moving the signal lever on your own.

Since we have found that the turning signal relay is an essential component of the car and it helps in the operation of your vehicle, always make an effort to have it fixed as soon as possible in case it exhibits some symptoms of malfunction.

Symptoms Of A Bad Turn Signal Relay

One of the most important things you should know as a driver are the symptoms that are associated with a faulty turn signal relay. This will help you to notice early when your turn signals are not working properly.

When you start seeing these symptoms unfold, you will act accordingly by taking your car for a check-up and if possible make a replacement of the faulty turn signal relays. Some of the symptoms to look up for include;

Turn Signal Relay Do Not Function

One of the most common symptoms of a faulty turn signal relay is a broken flasher. When the flasher is broken the lights won’t be able to function completely anytime you press the hazard light indicator.

This problem is unusually not connected to the engine in any way. This means its malfunction cannot affect the operations of the engine.

Despite not having any effect on your engine it can still be very dangerous to drive with a faulty turning signal relay. This is mainly because other motorists will not be able to tell your intentions and this can lead to fatal accidents caused by collisions. In case your turn signals blink so fast, then there is a possibility of a blown bulb.

The bulb can easily be replaced and won’t cost much. If it is the flasher that is broken, then you have to change it immediately. Before replacing your turn signal relay, always check the flasher relays for turn signals or hazard lights because in most instances they are put separately on some vehicle models. The first step would be to purchase a new turn signal switch.

You can look for the relay cluster location. Most vehicle owners’ manual booklets have specific models that can help you replace a new one. One important thing is that there is only a single method that you can utilize to insert the relays. So it won’t be much difficult to install it correctly if you choose to do it yourself.

Turn Signal Relay Stays On

Sometimes you will notice that your turn signals will stay on continuously instead of flashing on and off. When this happens, then it is most likely that there is a problem with your turn signal relay. Despite the lights being on, they won’t flash.

This increases the chance of other motorists wrongly reading your intentions. They won’t be able to decipher whether you want to turn left or right. This can be dangerous because it can lead to fatal collisions on the road. Turn signal relays not going off are often a result of electrical problems within your turn signal relay.

Additional Lights Do Not Work

Other lights beginning to fail is always another common symptom associated with a faulty turn signal relay. In some cases, you will have your headlights, brake lights, or even running lights starting to malfunction. This is because these lights have some sort of correlation with the turning signal relay lights.

When your other lights stop working, you should first check the turn signals lights to help you decipher the root cause of the problem. These lights may be sharing certain components such as the car battery, fuses, transformers, converters, and even capacitors. So when other lights have problems, it’s likely this will affect the turn signal relay lights.

Switch And Dash Indicator Problems

A faulty switch can be one of the reasons why the turn signal relay fails to function. It is essential to check the parking lights that usually make use of the turn signal light bulbs. If the parking and the hazard lights come on but that side does not illuminate when you hit the switch, the main cause of the fault is a bad circuit.

Many modern-day cars use turn signals that are integrated into brake housing using the brake lights themselves as turn signal lights. On some of these cars, it is possible to put these bulbs in backward and this can cause the circuit to fail in the lights and dashboard indicators.

Fast Or Slow Flashing

When the four-turn signal relay lights flash either too fast or too slow, then the problem can be traced from the flasher. If it is only happening on one of the sides then the problem could be the bulbs.

It is the bulbs that determine how much power goes through the flasher and how quickly it heats up. It is worth noting that high wattage bulbs draw more amperage causing the flasher strip to heat up and cycle faster.

NOTE: It is advisable to always inspect your turn signal relay indicators before hitting the road to ensure that they are in perfect working condition. Some issues could just involve simple fixes but you have to first trace the root cause of the problem. You can check for anything that is not in the position or for a possible disconnection within the system.

In case the relay signal is completely broken, then you should have it replaced before getting your car on the road. Some of these fixes are so simple that you can do them on your own using the owner’s manual but if you don’t have any basic skills, you can seek the services of a mechanic to help you fix the problem. This will be less costly.

How To Diagnose A Faulty Turn Signal Relay

The turn signal relay lights will always fail at certain times due to wear and tear. This is mainly the reason why they may stop functioning. The causes for the failure could be traced from the failing turn signal relays.

For you to be able to identify if the signal relay may be the main culprit to this problem, you will have to check the entire electrical system. You may have to check for any cracked, broken, or disconnected parts.

A faulty electrical system may be the major factor causing the turn signal relay to fail. The problem identified in the electrical system will have to be fixed first before proceeding to check the other components of the turn signal relay.

If there is any blown-out fuse then it has to be replaced with a new one. A problem whose root emanates from the electrical system can cause the turn signal relays not to perform effectively. In extreme cases, it can even lead to a complete breakdown of the turn signal relay.

How To Troubleshoot

In case you replace your turn signal relays with new ones but you still find out that the problem is not yet solved, you will have to take the next step. This would mean carrying out further tests to troubleshoot your car. The main purpose of this is to help determine the root cause of the problem.

Sometimes this process can be so frustrating especially if you try all the possible ways that can lead to the solution but still find the problem far from being solved. Here are some of the extra steps you can take to troubleshoot your car.

Check The Connections

One of the best things you can do is to inspect all the electrical connections when you still have the turn signal relay problems even after replacing them with new ones. You can start by inspecting the turn signal housing at the back of your turn signal.

You can also check on the different plugs that connect your turn signal to the electrical system. Unplugging then plugging them back can help reset them back. This can also help to ensure that they are plugged in properly in case they have been loose. If the plug connections are worn out, then you will have no option but to replace them with new ones.

The steps will help your turn signals to start working again. It can be a simple but crucial fix to the problem. The turn signal relay is a very delicate system that just a slight loose plug can set off the entire system.

Check Random Fuses

The next step in troubleshooting your turn signal relay would be to inspect the fuses any time you replace your turn signal relays. You may have to look up a fuse that has blown up somewhere within the electrical system.

A blown fuse will cause the turn signal to fail. Since these vehicles components have some sort of co-relation, you may find out that a bad circuit that serves another different system within your car may eventually affect the electrical system of the turn signals as well. The entire electrical system has to be in perfect condition for the turn signals to work.

If any of the circuits is cracked, broken, unplugged, or becomes loose, the entire system will eventually fail. It is necessary to check all electrical cords to find out if there can be a small problem causing turn signal failure.

Look For Bad Grounds

One final thing that you can do is to inspect for any possibility of a bad ground connection. There could be some bad wiring somewhere within the electrical system that is causing the turn signals to fail. In most vehicles, you will find that the wiring that is associated with the turn signal lights is often insulated using brown and black rubber material.

This makes the wires to be easily identifiable within the electrical system. You can inspect these connections to see if there could be something that is not correct with them. You have to make sure that the wires are connected correctly and none has broken away from the terminals.

Ensuring that the wires are plugged in correctly will also be of great benefit in helping to fix the turn signal problems. Those wires that are supposed to be screwed, make sure that they are screwed correctly. You can try to loosen then tighten the screws again to make sure that the grounds are working properly.

Replacement Of A Faulty Turn Signal Relay

After determining the root cause of the problem causing the failure of the turn signal relay, you have to arrange for the problem to be fixed as soon as possible. Failure to do so and continuing to use your car on the road may eventually lead to fatal accidents.

The signal relay helps you to communicate with other motorists on the road by helping them to know your intentions whether you are going to turn left or right. It also helps other motorists to know when to overtake you safely.

Turn Signal Relay

As we had mentioned earlier, some vehicle components have some sort of correlation. Ignoring a problem that is associated with the turn signals may eventually affect other parts too and lead to very expensive repairs. Riding on the problem for a very long time and letting it persist isn’t healthy for your car. It may trigger other bigger problems that may be very expensive to fix.

However, there are limited options regarding the repair and replacement of your turn signal relays. These options include;

Replacing The Parts On Your Own

To take this route, you first need to consider the depth of your knowledge regarding this type of job. The skill and the confidence in fixing your turn signals on your own are vital.

  • First, you will have to purchase a new signal relay from an auto shop near you. You have to ensure the one purchased matches the current one on your car. This helps you put the correct part that will ensure your turn signal signals begin working again.
  • Next will be to locate the position of the relay cluster. This is a point where several electrical components assemble. If you don’t know where it is you can always refer to the owner’s manual. It can help you locate the position of the cluster.
  • The last step is to remove the old turn signal and replace it with a new one there is only one way to fix this so you will hardly go wrong.

This procedure is not complex but you still need to have confidence in your ability so that you don’t end up damaging other components of the system.

Taking The Car To A Certified Mechanic

Having your car inspected by a qualified mechanic saves you the hassles of trial and error. They can help diagnose the exact problem within a very short time because of their experience and having the right tools for the job.

Though this option may be capital intensive it is worth it. A mechanic may identify more underlying issues and diagnose them early enough. The mechanic will fix everything for you. So you don’t have to peruse through your owner’s manual or remove some parts on your own. Having a professional handle your car is the best option to take despite the high cost involved.


Fixing your turn signal relay is not such a difficult task. With the right knowledge and tools, you can just do it on your own. But in case you don’t have the confidence in your ability, then you have the option to seek the services of a qualified mechanic. Don’t ignore any fault that involves the turn signal relay.

This vehicle component can seem simple but it’s very important. It will save you from putting your life and that of other road uses in danger. Failure to replace a bad turn signal may compound more issues that can eventually become expensive to fix.

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