How to tell if headlight ballast is bad

How to tell if headlight ballast is bad

How can I tell if my headlight ballast is faulty? When my HID lights won’t turn on, how can I tell if the fault is with the ballast? Could it even be as a result of a bad headlight relay? Is it best to buy a new system if my lamps do not light? I know you’re having trouble with your lights when you start asking these questions. 

There are different reasons for this, one of which is the failure of the HID ballast. You must check and troubleshoot your ballast to determine its condition. The state of your HID ballast will be indicated by what you see.

Signs that your ballast is bad

Signs that your headlight ballast is bad

Before you go out and buy new ballast for your lighting system, check to see whether it is the source of the problem. If you don’t, you’ll be wasting money and time.

  1. Headlights that dim or flicker

A ballast failure is most likely the cause of your HID bulb’s inability to provide full brightness or flicker regularly. While this attribute can also be associated with low headlight beam, when ballast starts to fail, it may have trouble regulating and producing a constant current, resulting in your headlight bulb dimming and flickering.

  1. Unusual noises

If you hear weird sounds in your HID bulbs, such as buzzing or humming noises, it signifies that your ballast is constantly running even when it is turned off. Your ballast may be having trouble maintaining current, resulting in an audible voltage regulation issue.

  1. If your headlights are not working

Check the entire system if your headlights aren’t operating or responding to your switches. If there are no loose components and the bulbs’ filaments are still good, there’s a good possibility your ballast is bad. But if they are, you might want to change your car’s headlight bulb quickly. 

  1. Changing the colors of your headlight

Your ballast may be malfunctioning if you see inconsistent colors or excessive brightness. The ballast may experience intermittent voltage fluctuations as the system ages. It’s possible that if you don’t change them fast enough, your bulbs will break.

  1. Continuous blowing of fuse

A faulty ballast is most likely the cause of constant fuse blowing. When your ballast can no longer regulate the voltage effectively, it may cause an increase in your electrical system’s current, leading your fuse to blow. Check your ballasts if you’ve been replacing your headlight fuses more frequently than usual recently.

Checking the ballast

Checking the headlight ballast

Aside from looking for indications that your ballast is failing, it would be best if you also examine the ballast directly. If you notice any of these indicators of damaged ballast, try resetting it or replacing it with a new one.

  • Damaged casing

Voltage overloads are the primary cause of a damaged or bloated case. Check your ballast power supply and fuse since these may cause issues with your replacement ballast if they aren’t handled.

  • Marks of burn

When you open your ballast cover, you’ll notice these burn marks. It’s caused by a surge in voltage that could cause the capacitor to blow. Because it regulates the voltage level that goes through the system, this component is usually damaged. It’s also a simple item to replace, so don’t be anxious if it becomes damaged.

  • Damage from water or oil

If you open your HID ballast and notice moisture or oil within, it may be faulty. It can also short out your lighting system, causing it to fail.

If you see some of these indicators, your ballast is faulty and has to be replaced.


Check your ballast if you’re seeing the above complaints in your HID lighting system. It may be past time to replace or repair them. Also, ensure you restore your car headlight lenses using a restoration wipe. Because losing  your lights on a dark road is not a good condition to be in, you should detect problems before they occur.

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