How to Fix Car Light Dimming and Brightening

Car lights are useful in navigation, indicators, and visual inspection of objects while driving. What then should you do if your car lights start Dimming and Brightening?

Shaky car lights are likely encountered on the stop, while idling with the defroster on, slowing down and speeding up your vehicle.

Whatever the case may be for your car, it’s necessary to know the necessary causes and how to fix a Dimming and Brightening Car Light.

Failure to fix a Dimming car Light will likely get you in trouble with the law, endanger other road users or cause you to manually do things that your car lights are supposed to do – highly risky.

Some of the fixes to a Dimming and Brightening Car light(s) are to get a bulb replacement or check the wiring harness of the light system.

Notwithstanding, faulty car lights are a prominent issue and should be fixed immediately it comes up for an enhanced driving experience.

Without wasting much time, let’s take a look a look at some of the possible causes of Dimming and Brightening Car light(s) and possible ways to fix the problem.

Car Lights Dimming and Brightening – Causes

Some of the major reasons why your stable car light will start malfunctioning are listed and explained below.

1. Faulty Bulb

Since the bulb is the main suspect once the light starts blinking then it’s expedient to visually inspect the bulbs on the Headlights, fog lights, and frontal lights.

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If you notice that one bulb illuminates brighter than another then it could be that the bulb in question is weak and needs replacement. Since all auto parts have a lifespan, it could be that are due or it has worn out due to excessive usage.

Also, make sure to get the correct bulb replacement to avoid getting lower illumination.

2. Problem with the Wiring

A problem in the wiring harness of the bulb system will result in it giving out low lights.

This includes poor connections, worn-out wires, short-circuiting, or a faulty electrical system.

At times, a bad battery or alternator also gives off these signs; so do well to monitor each of your car components.

3. Damaged Headlights

If your Headlights are been exposed to excess sunlight, dust, or dirt, it could give them a yellowish color which will also cause discoloration of the lights emitted by the bulbs.

4. Dirty lights

Likewise, if your bulbs are in constant contact with dirt or sunlight then it could get into the bulb(s) and cause the light to give off lower light.

5. Mechanical Faults

Mechanical Faults such as damage in the light chamber or lens can affect the illumination of a bulb.

How to Fix Car lights Dimming and Brightening Issues

A Dimming and Brightening Car light should be fixed if one or more of the below DIY guides are implemented.

1. Get a Bulb Replacement

A bulb replacement is the first thing that should come to a car owner’s mind but it’s also necessary to troubleshoot the bulb(s).

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You can do this by connecting it to another source and seeing if the brightness is still the same. Also, check for dirt accumulation or if there’s a break.

In addition, it’s necessary to go for high-quality bulbs with quality bases. The lifespan of the bulb should also be put into consideration.

2. Check the car Battery and Alternator

A low power supply from the battery could result in a Dimming and Brightening Car light.

You should consider checking the battery and alternator for green matters on it. You can also make use of a jump starter or get a new battery at most.

In the case of an alternator, you can check out the alternator belt and also get a new alternator if necessary.

3. Check the Wiring Harness

Light fluctuations can also arise if the wiring harness of the electrical system is problematic.

You can perform a visual inspection and replace faulty wires or open connections. You can also apply tape to naked wires on the wiring.

4. Cleaning the Headlights

For better illumination, it’s necessary to clean the exterior of the Headlights with a moist cloth and if it’s a case of water then a visual inspection is needed.

You can also proceed to remove the streaks from the lens and apply toothpaste or sandpaper.

5. Replace the Light Assembly

You must remove and replace the light assembly if that is the problem. Mechanical deterioration may be the cause of this issue, and unless you do not make improvements promptly, they could become significant. Make sure you have the appropriate replacement in order to avoid a recurrence of the problem with the lights fading and brightening.

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Q: Why Do My Lights Get Brighter When I Speed Up?

The alternator’s voltage regulator may be the issue if your lights intensify when you speed up. The regulator’s job is to maintain the power outflow in order to avoid a surge as the alternator’s speed increases. The regulator is not problematic when the lights are brighter.

Q: Why do my car lights Dim While Driving?

When you’re driving, your car’s lights may dim because of a problem with the alternator or the wiring. It indicates that the ground wire in the wiring unit deteriorates. To avoid this issue recurring, make sure your electric connection is tidy, especially if you are working with a broken ground wire. Another sign of the issue could be dimming lights when the engine is revving.


One issue that can be very frustrating for drivers is when their car lights dim and brighten suddenly. This can make driving challenging and increase the risk of accidents. This problem has a number of root causes, including bad connections, burned-out bulbs, and dirt. To find the best solution, you must first identify the issue through inspection.

You may learn more about this problem and how to handle it in-depth in this post. If you run across a problem, you may use our expert advice to assist you to deal with varying brightness in your car lights.