Why Does My Turn Signal Blink Fast?

Your vehicle’s turn signal indicators may seem the simplest of parts, but they are crucial in the way our highways operate safely. These turn signals allow other drivers that share the road with you to know ahead of time which way you are going, and thus, be able to prepare and avoid hitting you in the process of driving. Now while the process by which the light flashes may at first look like it's the most straightforward electrical connection, it is nevertheless an important and an essential part of motoring.

This particular system of your vehicle can experience problems in the lifespan of your vehicle, and one of the most often to happen is why this turn signal blinking fast than normal. This is important because this simple electronic malfunction can point to other, more serious problems. When both turn signals blinking fast happen to your car, never take it for granted as it is a signal for you to take a closer look at your vehicle’s electrical system. We understand you are here to find out why this rapid flashing turn signal happens and we promise to deliver so let’s get right to it!

How Do Turn Signals Work?

Let’s start with how normal turn signals operate in order to understand what makes them go on the fritz. When you turn the signal stalk, a fused hot wire delivers power through the flasher module which in turn originates from under the hood. This wire provides the power for the flasher module to the stalk which is located in the steering wheel sides along the steering column. When you toggle the stalk upward or downward to the direction you are going, the circuit gets completed and power goes to the corresponding bulb.

However, because of the flasher module the power momentarily cuts off in timed intervals, thus producing the flashing light other drivers see on the road. The flasher module uses a heat sensitive contact where it expands and contracts and that action bridges and cuts off connections. This action is based on resistance and is directly affected by a bulb’s filament. Part of what causes a turn signal to flash faster than usual is when this filament is broken, which produces less resistance.

What Causes Turn Signal Blinking Fast

Before we can address how to fix turn signal blinking fast, we need to really take more than a closer look as to what makes this fast blinker event happen. To give you the most comprehensive article possible, we scoured all the sources of information available to us and came up with all the possible causes below. There are a myriad of possible causes, but the information below should help alleviate some of the confusion.

Insufficient Voltage

One of the most common reasons you might ask why does my blinker blink fast is that the electrical system of your car is not supplying enough voltage. You can diagnose this if you have a multimeter or a basic tester and of course basic knowledge in car wiring systems. When you have confirmed that the turn signals flash fast even with new bulb, it is time to further check the electrical system of your vehicle. In short this symptom should serve to point you to a physical inspection of the car’s electrical parts and connections.

Bad Bulb

It can be due to wear and tear, old age, or just a bad product but bad bulbs and aftermarket replacement products can be an all too common reason for your blinker blinking fast problems. A damaged bulb can wreak havoc with your blinker as they may not have enough resistance to properly trigger the flasher relay. Poor aftermarket bulbs can affect how your flasher relay works, and the worst part is that it can damage the entire system. These lemon bulbs should be easy to isolate, especially if you have not touched or modified the original wiring.

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Another bulb – related issue is that the blinker is clicking fast but bulb is good and there is no lights out. The reason for this is that some flasher relays cannot handle LED bulbs or you may just have bought a defective bulb. With this, it is always best to stick with your OEM ( original equipment manufactured ) parts and what the manual recommends. It is also good practice to test out any bulbs you buy to ensure they are working before putting them in your vehicle. Make sure you replace one that matches your old brand, or at the very least the same specifications electronically.

Damaged Connections

Sometimes you can also experience that only the left blinker blinking fast and at other intermittent times the right blinker blinking fast. This is your cue to start checking the quality of your wires and terminals. These would include corroded wiring,worn-through terminals, loose connection points, and rusted out parts. Check out the physical condition of your flashers and relays,, especially the internals. These are robust little pieces, but when the rest of the components are compromised they can easily get affected as well.

Replacing these parts are quite easy and straightforward, but you do need to be careful to match the specifications, particularly the voltages and amperages. For the wiring, the factor to watch out for would be the gauge which is how thick the wires should be. While it would be optimal to have an experienced auto mechanic tinker with the wiring, it is easy enough to DIY especially if you have the time and the tools. Remember any exposed wiring, corrosion and rust, or loose connection is alway a potential for something to go wrong.

Turn Signal Relay

A bad turn signal relay is also one of the most common causes of flashers blinking faster than normal. The good thing is that this is a fairly common part that is available almost anywhere. Take a look at this part when the fast blinking is still happening even if you have already replaced the bulb. Another great thing about this part is that it can be had for a fairly reasonable amount. It is a good idea to stock up on this in case one gives out in the middle of a drive.

Take note though that this is a slightly more complicated procedure than a fuse replacement. There is also a need to check the socket for damage, and there is a chance that you also need to replace that as well. As you check the relay, it is also a good idea to thoroughly inspect its socket for burn marks and signs of wear and tear. Pro tip is to get a ceramic socket instead of the usual plastic ones.

Turn Signal Fuse

Fuses are small but if one gets blown, your car may not even start. These handy little things are the difference between your ride going up in flames or a long life ahead for your vehicle. A fuse will disconnect any circuit in case of shorts before it can cause any damage. Like the relay you should have spares with at all times as these are quite cheap. Make sure you have the correct amperage with you because they differ in this regard. Fortunately, a blown fuse is literally a plug and play affair, just make sure you have the correct amperage. This should be clearly marked on the fuse’s body so there is very little chance of mistakes.

Ways to Fix the Turn Signal Blinking Fast

Yes it is true that there are a lot of chances for the turn signal to get messed up, but fortunately there are fixes for every single one of them. They are simple enough to do by yourself when you have tools and they are also not going to break the bank should you decide to go to your trusted mechanic for the fix. We went ahead and got some of the most common ways to fix your turn signal in the event you find yourself in the situation where you need to.

Some hack you can wathc in this video:

Check Turn Signal Operation

As usual when trying to troubleshoot a car problem, do a quick walkaround of your vehicle and see if there are obvious signs of things that do not belong. In the case of a buster blinker, always check first if your turn signals are working properly and as intended. This would include checking if the turn signal has that tactile click and feedback when flicking or turning them. This should be done just so we can eliminate the simplest of causes for the problem. It does not make any sense when you already ripped out the dashboard looking for the problem only to find out that it was the signal stalk that is causing the problem. Physically check that all lights around your vehicle correspond accordingly to the direction you point your turn signal indicator.

Fixing Faulty Bulbs

Check the bulb’s physical condition for burns, rust, or corrosion on the terminals as well as the bulb’s filament itself. Note that popular LED bulbs may cause flasher relay problems as well on older vehicles. Go with the manufacturer’s recommendation or better yet, get the same exact bulb type that you removed just to be on the safest side. Replacing the bulbs can be an easy fix that you can do yourself, saving your hard earned money in the process.

Damaged Wires

Check the condition of the wiring of your signal lights, at least those that are visible to you. This is one of those rare instances where you may need to visit your local trusted mechanic as the wiring may be hidden and can be tricky to get at. A professional is much better equipped if ever you come to a point where this needs to be checked. Nevertheless, this should not break the bank in case repairs need to be done.

Working on the Relay

Remember when we said to have some spare relays always in the glove compartment with you at all times? This is where it comes in handy, as you simply need to locate the relay and plug in a new one to try and fix the problem. If the relay is the problem, replacing it should fix the problem immediately. If this does not solve the problem, move on to other areas.

Correct Resistance Related Issues

This is why LED bulbs will not work properly on older cars because the flasher relays are driven by resistance. LED bulbs have very low resistance as it takes so much less current to power them and make them work. This messes up the circuit and makes the flasher behave abnormally, usually by speeding up the flash intervals and eventually damaging other components. Make sure that the replacement bulbs have the same voltage and resistance ratings to ensure that they would work properly.

As always, we do not want you missing out on vital information, so we gathered all the most common questions everyone asks regarding rapidly blinking flashers. Read on below:

Frequently Asked Questions (FAQs):

Is a fast blinker illegal?

Anything above 120 blinks per minute is illegal according to the Department of Transportation. If not it should be illegal as this will only cause a dangerous distraction on the road. Other states may actually outlaw flashers that are below 12 blinks per minute so this is largely dependent as well on your location. Just to be on the safe side of the law, stick to the stock flashers of your vehicles.

Where is my turn signal relay?

The location varies from vehicle to vehicle but they are usually located together with the fuses underneath the steering column or its general vicinity. When you cannot find it there, the only other place it could be is inside the fuse box under the hood, usually located beside or near the battery.

What is a LED flasher relay?

These are what is used by most modern cars today, and are electronically controlled instead of being dependent on resistance. They can do more complex light actions like sequential turn signals and are quite cool to look at as well as more visible.

How do you test a turn signal flasher relay?

A multimeter as well as a tester can easily determine and check whether or not a relay is working properly, but is best done by an automotive electrician. First the location of the relays differ per vehicle and you may take some time finding out where the relay is, and secondly you may not have a multimeter and a tester at your disposal, as these are specialized equipment that only electricians will most likely have.

How much does a turn signal relay cost?

This is a pretty inexpensive car part so it should not be a problem cost-wise. In fact, because they are so cheap, it is a great idea to have a couple of spares in your trunk just in case. They are also quite easy to replace which involves just pulling off the old one and plugging in the new one. This is unless the sockets are not damaged, in which case you will need a trip to the shop to have it fixed. The labor cost is usually more or less 100$.


As with any car related fixes, an ounce of prevention is always better than spending thousands of your hard-earned money in a shop just because of negligence. Never take a flasher problem for granted as they usually point to a bigger car problem in the long run. When this happens always check the details that we outlined above and you are well on your way to enjoying a long driving relationship with your car.

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