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What is Causing your Car Lights to Flicker?


If your dashboard and car lights are flickering and flashing this means there is a problem with the electrical system. Driving with flickering headlights is quite dangerous on the road and you need to take care of this problem ASAP!

The malfunctioning alternator may be one of the causes of flickering headlights. The battery is required for the correct operation of your headlights and if they are flickering or dimming, you either have a bad battery or an alternator that is unable to charge it.

These are two main components of the electrical system and common reasons behind flickering lights:

  1. Battery. Besides giving the initial boost of power for starting a car, the battery is in charge of powering all your electrical equipment along with lights. If the alternator is not charging the battery properly, all car electronics, including power windows, steering, and audio system will start “behaving” irrationally.
  2. Alternator. The purpose of the alternator is to distribute electricity throughout your vehicle and recharge the battery. When your alternator is functioning correctly, it will automatically charge the battery and maintain power to the vehicle’s electrical system.

Besides that alternator problem and a weak battery, your lights could be affected by a faulty bulb or a problem within a corresponding circuit. If your lights are flickering while you are trying to start a car, you could have a problem with the starter as well.

It is very important that you take care of the flickering problem as soon as possible, because you may just end up in the middle of nowhere with no power …

Now, let’s dive into the details:

Common types of flickering problems

Flickering lights are a very common problem in a car. Solving this type of problem usually starts with testing a battery and alternator. A healthy battery in a car is usually at:

12.7 – 13.2 volts

If its voltage drops below 12.65, it may not be able to keep up with its job and you will have a problem. Failing battery usually results in dining or flickering headlights or dashboard lights.

Lead-acid crank batteries usually last for about 3-5 years and maybe it’s time to get them replaced. Your battery life cycle also depends on how it was used.

If your car is sitting in a garage for a while, there is a good chance that your battery went dead. When your battery is not receiving enough charge and its voltage gets below a certain point, the alert light in form of a battery will illuminate on the dashboard.

The failing alternator will have a problem charging a battery and may cause lights to flicker at low RPM. This flickering may disappear at high RPM while driving, but it doesn’t mean that your problem is solved!

You may want to check the alternator’s belt tension and make sure that it is not frayed or damaged. In order to solve your flickering problem, you may need to change the alternator belt or the alternator itself if it is damaged.

Car lights flickering while idling

If your car lights are flickering while idling at low RPM, it is generally due to the battery or charging system failure. It could also cause cars to run rough.

In this situation, the battery and alternator should be tested by a qualified specialist. AutoZone offers free testing. Flickering lights is always an electrical issue and all parts of it should be inspected by a specialist.

Car lights flickering while driving

If your car lights, especially headlights are flickering while driving, it is not just annoying, but dangerous! When your lights start going ON and OFF frequently on the road, the first thing you need to check is the bulb itself.

The bulb could be weak and getting to the end of its working life. More complicated problems in this situation include alternator failure and dying battery.

They also should be tested and replaced if necessary. You should also inspect your wiring connections, relays, and switches for being worn out.

The problem is with intermittent power supply, that goes ON and OFF and you need to find out what exactly is causing it. Electricity is not simple to troubleshoot and you should visit a licensed professional for that.

Car lights flicker when accelerating

If you notice that after stepping on the gas all the lights in your vehicle start to flicker, this is usually due to one or two diodes failing in the alternator. In this case, the flickering will be activated when the RPM increases.

Car lights flickering while the car is OFF

If your car is OFF, but the dashboard lights are flickering and going crazy, this is probably due to the loose battery cables. The first thing you need to do is inspect your battery posts for corrosion.

Don’t forget to use safety glasses and gloves, since you don’t want to burn your skin with acid. To clean your battery, you can use baking soda with water.

After cleaning and tightening battery terminals, you can lubricate and seal them to prevent acidic buildup and corrosion in the future. If your battery terminals or cables are damaged, find a professional to help you out.

Car lights flicker when trying to start

Sometimes your starter can be a cause of the flickering or pulsating dashboard lights in a car. In this case, your starter will need to be replaced.

When you are dealing with flickering car lights, it can get very confusing, since we all know that a bad battery or alternator is a more probable cause of this. If you are getting flickering lights during car startup, you may be dealing with a bad starter and that is especially true when your engine fails to crank.

The cause of headlights flickering

In headlights, flickering may be caused by bulb filaments that become worn out or damaged. There also may be a problem caused by the circuit itself.

Damaged wiring or poor connection may cause intermittent supply of electricity and therefore a flickering effect. 

Short circuits could also be a cause of flickering headlights. This is especially true in older cars with built-in circuit breakers. OLder car models have flickering problems a lot more often than newer ones.

Switches and relays that have gone bad could also create problems with flickering lights. They could be tested with a voltmeter or multimeter and changed if necessary.

Your headlight socket could also be damaged and cause a poor connection. Issues with alternators (or their voltage regulator) very often can be a cause of flickering headlamps or car lights in general.

The power output becomes inconsistent and your headlights start to flicker.

Dashboard lights flickering

All the components in your vehicle as a whole need a steady supply of power to be useful. If your alternator and battery cannot supply it, onboard computer will start prioritizing and selecting which circuit to power first.

This is why dashboard lights (along with other lights) may start flickering.  It basically means that they are not getting consistent power from the electrical system.

Along with flickering, you may also notice that some of your lights are dimming and certain electrical gadgets (like radio, power seat, power windows) will completely stop working!

Why? Because your vehicle’s computer is very smart and it selects the most vital parts of it to power, so we don’t get into too much trouble.

Even though the alternator is a very rugged and stable component in a car, is very important to keep your eyes open if it gets to the point of outliving its usefulness. It may give you some signs in the form of strange noises coming from the belt area BEFORE the actual flickering problem takes place.

Getting a new alternator doesn’t have to be expensive and you can get one fixed or rebuilt. Of course, you could also get a new alternator for your car if needed.

Can a bad battery cause lights to flicker?

Yes, a battery (being a key component of the electrical system) can become a cause of your flickering lights. If your dash lights and headlights are flickering, it is highly likely that a bad battery is a problem.

Of course, it doesn’t stop there. If your battery is brand new and you have this problem, there must be something that is preventing it from being charged. While testing your battery, you should test your alternator as well.

Just changing a battery if your alternator is not producing enough power is NOT a good idea, because it will go dead again!

Need to solve this flickering problem fast? Find a professional near you:

Attention! This article is for informational purposes ONLY and is NOT a replacement for professional advice! ALWAYS consult your local specialist for an appropriate solution to your problem. All statements, prices, contact information, recommendations, and reviews contained herein came from sources that we believe to be reliable, but the accuracy or completeness thereof is not guaranteed. Please contact the service provider for complete details and updates.

1 Comment

  1. Gary Downs

    On my 2008 Buick Super there is a battery current sensor located on the negative battery cable near the battery. I had to cut the factory terminal clamp off to install a new sensor (I left the crimped part of the factory clamp on to insure I had enough length, and reinstalled a large size cable, generic, aftermarket clamp). The flickering went away.
    Prior to the new sensor, my onboard voltage meter was giving me readings ranging wildly from 14.7 to 12.4 volts during charging, staying at over 14v for extended times. Now I get readings at a stable 13.2 to 13.6, depending on current load.

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