Why are My Car Headlights and Dash Lights Flickering

Driving with a flickering car headlight can create unsafe conditions on the road because they can create distractions for you and other drivers.

If you are wondering why your car headlights and dash lights flicker when your car is running, then you are on the right page.  There are many reasons why your car headlights may be flickering.

What are flickering headlights?

Generally, flickering headlights are caused by a false bulb or a problem in the headlights circuit.

A broken light bulb usually causes flickering headlights.

If your headlight lens shows off while driving, here are the most common reasons:

  • Failing bulb

If you have halogen bulbs, the flickering may be caused by the filaments being damaged or worn out.

Car Headlights and dashlights

Most often, this is a publication signal that your headlight is nearing the end of its life.

There are different types of headlight bulbs, each with an expected life.  Halogen headlights usually burn hot, typically have a shorter service life, and will fail faster than others.  If you have an older vehicle or even a newer, mid-priced model, you probably have halogen bulbs in your headlight.

High-end vehicle models are often equipped with light-emitting diodes (LEDs) or high-intensity discharge (HID) lights, which tend to last much longer.

  • Headlight circuit problem

Flickering headlights may also be caused by a circuit problem.  For example, the issue may indicate damaged wiring or a bad connection.  It may also be to blame a bad headlight switch or relay.

Car Headlights and dashlights

The headlight switch for older vehicles includes a built-in circuit breaker, and when it comes to a short circuit, this can cause the car headlights and dash lights to flicker.

That is why flickering headlights are mostly common with older models.

  • Weak battery

Your car battery usually starts showing up the signs when it is near the end of its life – one of them may be flickering headlights.

A weak battery might not have sufficient power or capability for your headlights so they will eventually dim or flicker.

In general, car batteries can last around 3-5 years.  Several factors can affect the life of your battery, such as the condition of your vehicle, your driving habits, or the weather conditions where you live.

Car Headlights and dashlights

If there is nothing wrong with your bulbs or headlights, you can check the battery for issues as it might be the time for your car battery replacement.

A weak car battery can cause dim headlights.

  • Failing alternator

A problem with the voltage regulator, which is often located inside the alternator may cause the car headlights and dash lights to flicker. Such problems with the charging system may lead to inconsistent current output, which may dim your headlights.

If you blame this component, you will probably observe a few other common symptoms that point to a bad alternator.

Car Headlights and dashlights

It is important to diagnose this problem immediately, so you or your mechanic can fix your flickering headlights as soon as possible.  If you lack technical knowledge or DIY skills to solve the problem, it is recommended to leave this job to a professional.

Diagnosing your headlights

As previously discussed, flickering headlights can be caused by one of several potential factors.  Once you’re excluding the battery and the alternator, there are other ways to diagnose your flickering headlight problem:

Visual inspection

The first and foremost action that you should be performing is to have a visual inspection.  Look for issues, such as:

  • Damaged wiring
  • Burnt out light bulb
  • Damaged headlight socket (s)
  • Independent electrical connections

Use a Scan Tool

Car Headlights and dashlights

If you have the DIY skills  and a scan tool, you can diagnose a broken headlight by following the below steps:

  • Rotate your headlights using your scan tool with the bi-directional command.  If they ignite, this means that the problem is not in your headlight.  The problem is most likely related to the control input to the specific controller that controls the headlight.
  • Determine the location of the open circuit by checking the voltage in different parts with the schematic for the headlight circuit.  Make sure you always follow your repair manual.
  • If your headlights appear brighter than normal, the problem may be related to a high battery voltage.  Check the charging system voltage and make sure it is less than 15.5 volts, which is the standard for most vehicles.  You can check the information to find the exact description.
  • If your headlights are dim as usual, this could be a sign that there is excessive circuit resistance, such as a loose electrical connection, a corroded socket, or a bad electrical ground connection.

You can diagnose your car headlights by either of the above two ways – a visual inspection or a scan tool.

Flickering headlights can cause accidents on the road.  If you notice that your headlights are not working properly, do not waste time, and immediately address this problem. You can place orders for the high-quality car headlights and dash lights at The Auto Parts Shop. You and your passengers’ safety should always come first.

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