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As inconvenient as it can be, your dashboard lights could dim or fail to activate entirely whenever you drive with your headlights on. In most cases, adjusting your vehicle’s dimmer switch while your headlights are on will increase the brightness.

However, there are other reasons why your dashboard lights might not work.

Why Do Your Dashboard Lights Dim or Go Out When Your Headlights Are On?

Dashboard lights usually dim when the headlights are on because the vehicle adjusted the dashboard’s brightness based on the light levels outside.

You might have noticed this in action when you drive in dark tunnels while the sun is still out. When you’re out and about in direct sunlight, your car’s dashboard lights are dim or off. On the other hand, driving in darkness causes them to light up instantly for clearer visibility. his happens because of automatic dimming control, though it’s important to mention that not every vehicle has this feature.

When you turn on your headlight, your car’s computer takes it as a sign that it’s dark out and brightens the dashboard accordingly.

The best way to stop your dashboards from dimming when the headlights are on is to adjust the settings of your dimmer switch. It’s usually on the left-hand side of the dashboard or sticking out of the steering column.

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What Else Can Cause the Dashboard Lights to Go Out?

Besides automatic dimming, there are other explanations for why your dashboard lights can suddenly dim or deactivate. Here are some of them.

Issues with the Electrical System

The electrical system powers various parts of the vehicle, including the dashboard lights. So if the system has problems like bad connections, corroded wiring, or blown fuses, then it could make the dashboard lights malfunction.

Problems with the electrical system typically develop when driving on rough roads. The bumps, constant shaking, and unsteady movement can dislodge connections and loosen up wires.

Conversely, wires and electrical components can also wear out and corrode when they’re exposed to the elements as well as foreign contaminants.

Malfunctioning Computers (CAN and ECU)

Modern cars have special computers that manage crucial functions. If these computers malfunctioned in any way, many parts of the vehicle such as the dashboard lights will stop working correctly.

Similarly, if the electrical system fails to provide sufficient power to these computers, you might experience the same problem.

But what exactly are these computers?

One of the most important parts of the vehicle is a computer system called the controller area network (CAN). It’s made up of electronic control units (ECUs) that control different parts of your vehicle.

Any complications in the CAN or ECUs can cause your ride to malfunction.

Sensors in Your Vehicle

Much like how turning on your headlights can cause sensors to dim your dashboard lights, a sensor that’s faulty might send incorrect signals to your computer. This potentially leads to the dashboard lights getting deactivated or dimmed.

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Sensors can also sometimes cause dashboard lights to dim or deactivate even when they’re working as intended. For example, your vehicle’s ambient light sensor might detect high levels of light outside your vehicle. It’ll send signals to dim the lights on your dashboard because it deems them unnecessary.

What to Do When the Dashboard Lights Stop Working

If the dashboard lights on your vehicle went dim or stopped working, your best bet would be to pinpoint the cause. Here are some steps you can do to diagnose the problem.

Configure the Dimmer Switch

Try fiddling with the settings of your dimmer switch to see if you can get your dashboard lights to stay up while your headlights are on. In some cases, people accidentally change the settings of the dimmer while driving. Readjusting it should fix your problem.

If nothing changes, there might be something wrong with the dashboard lights themselves. Check your fuse box for blown fuses and dislocated wires.

Check the Fuses

If there’s nothing wrong with the dashboard lights, inspect your vehicle’s fuse box. Check the fuses and wires connected to the dashboard lights for any damage, corrosion, or misalignment.

The wires might have gotten shaken or bent during a bumpy drive, breaking up the connection between the electrical system and the dashboard lights. Similarly, a fuse could have blown while you were driving.

Correct mistakes and replace blown fuses. If there’s nothing out of the ordinary, it’s a good idea to inspect the car battery and alternator to see if anything’s wrong.

Look at the Car Battery and Alternator

Finally, check your car battery and the alternator. Don’t forget to check the battery connections for signs of corrosion as well, and make sure they’re tight and secure. If the car battery and/or the alternator are corroded, dented, or misaligned in any way, these components are likely behind your vehicle’s malfunctioning dashboard lights.

Don’t forget to check the battery connections for signs of corrosion as well, and make sure they’re tight and secure.

Anthony Harlin, ASE Certified Master Automobile Technician
checking the car battery and alternator
If the car battery and/or the alternator are corroded, dented, or misaligned in any way, these components are likely behind your vehicle’s malfunctioning dashboard lights.

If you’ve inspected your vehicle from top to bottom and still haven’t found the culprit, it might be time to bring it to a professional.

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Frequently Asked Questions

Here are the answers to the other questions most people dealing with dashboard light issues ask.

Can Dead Car Batteries Cause Dashboard Lights to Fail?

Yes, a dead car battery can cause your dashboard lights to fail. After all, the battery powers your vehicle’s electrical system, giving all the electronic components enough juice to function.

Do Bad Alternators Cause Dashboard Light Problems?

Like dead car batteries, bad alternators can also cause dashboard lights to fail. Alternators are responsible for charging the car battery while you drive, which means a malfunctioning alternator won’t be able to generate enough electricity. A lack of energy leads to a dead battery, which then leads to dashboard light problems.

Can A Faulty Dashboard Light Fix Itself?

A faulty dashboard light is incapable of fixing itself. If you want to fix a bad dashboard light, you need to discover the root cause of the issue and address it directly. This might involve replacing damaged parts, charging a car battery, or adjusting the settings of your vehicle’s sensors.

About The Authors
Anthony Harlin, ASE Certified Master Automobile Technician
Reviewed By Anthony Harlin, ASE Certified Master Automobile Technician

Technical Reviewer at

Tony Harlin is a Master Gas and Diesel Diagnostic Technician with over 18 years of experience. He works full-time at a large independent automotive shop as a driveability and repair technician working on all types of vehicles with a focus on diesels. ASE certifications include A1-A9, L1 and L2, as well as X1.

CarParts Research Team
Written By Research Team

Automotive and Tech Writers

The Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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