Trucks, cars, and motorcycles: they all experience the same issue. Dimming lights turning on and off. You might be asking yourself, “Why are my headlights flickering?” You’re not wrong to wonder, because driving late at night without your trusty lights to guide the way can be a real safety hazard for you and other nearby drivers.
So, how can you identify why they’re turning on and off? What are some of the common causes of flickering headlights, and what are a few solutions?
Certified Fleet Services here. From spark plugs overheating to transmission fault repairs and more, our mechanics have worked with trucks for more than 25 years, so we’ve seen a thing or two.
If you’re looking for why headlights flicker, you’ve come to the right place. Let us walk you through why it happens so you can make more informed decisions about whether you need to bring your truck in for in-shop repair or just need to pull over for a quick roadside troubleshoot.
We’ll walk you through seven common reasons headlights flicker and what you can do about it.
7 Common reasons why headlights flicker
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1. Battery issues
A common reason that headlights flicker is because of battery issues. A dying battery, a low-powered battery, or even a faulty battery can be a cause for headlights flickering.
Since a vehicle battery tends to last three to five years, you’d be smart to check the status of your battery often. Also, note that if you take frequent shorter-distance trips, leave your car parked for longer periods of time, or live in climates with extreme weather, the lifespan of your battery may be compromised.
Finally, always check your electrical system as well. Your battery may not be the culprit, but a faulty electrical system may.
2. Failing alternator and other alternator issues
Another one of the common causes of headlight flickering is a failing alternator. The alternator’s job is to turn mechanical energy from a vehicle’s engine into electrical energy to power it, and most importantly, to recharge your battery.
If your truck is experiencing issues with the alternator, it may not charge your battery, as your truck’s electrical system relies on your alternator to power your battery. If you suspect any issues with your fleet vehicle’s alternator, bring your vehicle in for immediate fleet service.
3. Worn-out bulbs or lamps
This goes without saying, but worn-out bulbs, damaged lights, or old lamp wiring can cause headlights to flicker. The good news is that fixing a worn-out headlight bulb or lamp is as simple as bringing it into a diesel truck repair shop so they can replace the bulbs or lamps in question.
4. Loose electrical connections or fuses causing issues
Electrical diagnostics also play a large part in the operability of your headlights. If your headlights are flickering, they could be indicating that a fuse is loose, not pushed all the way into its socket, or tilts/wobbles when the vehicle is in motion.
This issue may be particularly pronounced when driving on uneven surfaces or rough roads. These issues can be tricky to diagnose, so we recommend having your electrical system checked to ensure it functions properly.
5. Faulty, loose, or corroded connections and wiring
Say you’ve taken a look at the four issues mentioned above, and your headlights are still flickering. Occasionally, headlights may flicker not because issues exist with the system, but with the wiring itself.
For example, the inside of the connector may start to melt, which can cause a poor connection to the bulb. Also, the wire may cause a poor connection to your lamps.
As such, you may need to replace the damaged wires and test it to ensure they work as they should.
6. Faulty headlamp switch
Sometimes, a truck’s electrical and computer systems won’t communicate with each other well, which can cause flickering headlights.
One other area to look at is your headlamp switch. Consider checking your vehicle’s computer system, electrical system, and any fuses or relays that could compromise either of these systems.
7. Tensioner or pulley slip issues
Common headlight components that require technician oversight include the alternator belt, tensioner, or pulley slip. For example, sometimes the alternator may work, but if the alternator belt slips, its output may decrease, and you’ll notice your headlights may start flickering or dimming.
If the tensioner is weak, if a pulley bearing is dragging, or if the belt is worn, you may also notice your headlights causing you issues. You may even hear a brief squeal at startup or notice flickering when the engine is working in strenuous conditions (such as when carrying heavy loads or blasting air conditioning).
These issues may be more pronounced on certain days or depending on the load carried, inclement weather, and moisture in the air. So, if you start to notice a pattern with weather or when your engine is bearing heavy loads, consider calling a truck or auto repair shop for in-shop or mobile repair work.
Common actions you can take when you notice headlights flickering
If you notice your headlights are flickering, here’s what you can do to help manage the issue or prevent it from becoming more serious in nature:
- Battery warning light turns on: If you notice your dashboard light turns on, consider limiting driving and inspecting your charging system.
- Flickering with rough roads and turns: If you notice your headlights flickering with bumps or turns, consider checking for loose connections in the wiring.
- Burning smells or odors: If you notice burning plastic or smells, pull your vehicle over immediately and call a diesel truck repair shop for immediate help.
- When flickering becomes more frequent and intense with time: We recommend bringing your vehicle in for an inspection to ensure the issue doesn’t result in you not being able to start your truck.
- When only one headlight flickers: Consider holding off on driving at night. Also, make sure to have your vehicle’s electrical system inspected to nail down the root cause of the issue.
Need someone to check your truck for headlight flickering?
We’re here for you. Fleet operators, managers, and drivers: If your truck’s headlights are flickering, you never want to wait.
Bring your vehicle to a diesel truck repair shop, because flickering or dimming headlights can be not only a hassle, but a serious safety hazard for you and other drivers.
Worst of all, if DOT officials find your vehicle without proper lighting, you could be fined or penalized operating i t. If you notice your headlights are flickering, why not bring it in proactively for preventive maintenance?
If you live in the South Florida region, bring it in to either of our Sarasota, Tampa, or Fort Myers shop locations. Our ASE-certified technicians have the tools, experience, and knowledge to get you up and running fast, the first time around.
No upcharges or bait-and-switch sales tactics, just helpful, reliable, and complete truck repair service.
To schedule a headlight inspection, get in contact with us today. Let’s get your truck powered up and fast.
