HID Troubleshooting: Why Your Bulbs Aren't Turning On Consistently

March 11, 2021 8 min read

HID Headlight

HIDs are a bright, powerful, efficient kind of headlight, and they're gaining in popularity with every passing year. Some vehicles come with them stock, but many require an upgrade kit to install them. As with any aftermarket upgrade, there's always a chance that something goes wrong, either immediately or after some wear and tear. 

One of the most common problems with HIDs is that they are inconsistent. They might fail to turn on every time or fail to turn on at all. They might also flicker.

So, what's going on, and how can you fix it?

How HIDs Work

HIDs are High-Intensity Discharge lamps, usually a Xenon bulb, in a projector housing. Traditional halogens and other incandescent light bulbs use a filament, which glows hot enough to emit light when electricity is passed through it. Much of the design of a halogen bulb is spent on isolating the atmosphere inside the bulb to protect the filament from anything that could damage it because once the filament breaks, the bulb is dead.

The biggest issue with halogens is that 80% of the power sent through it is emitted as heat, not light. That makes them extremely inefficient.

Xenon bulbs are different. Rather than a filament, the bulb is a housing enclosing Xenon gas. That gas, when sparked with enough electricity, erupts into a light beam. They're much more efficient and much longer-lived, in the right circumstances. 

The problem is, the voltage required to "ignite" a Xenon bulb is much higher than a typical vehicle can produce. Most vehicles operate with a 12-volt current throughout their wiring harness, but it takes a shocking 18,000-30,000 volts to ignite Xenon. Once ignited, it takes a much lower amount of power – around 90 volts – to keep the reaction going. When electricity is cut off from the bulb, the reaction stops, and the HID stops emitting light.

So, how do you get your vehicle's 12-volt system to produce 1,500x the voltage?

HID Ballast

A ballast. Every HID upgrade kit comes with a ballast system. The ballast is essentially a large capacitor; it stores up the voltage from your vehicle's system and can discharge it in a sudden burst to ignite the arc necessary to start the Xenon reaction. Once ignited, the ballast provides a trickle of power at the precise level necessary to keep the light going without surging it or dropping it too low.

At the same time, the ballast works as a converter from DC (direct current, from a battery) to AC (alternating current, like your house system). This means the current flickers back and forth, the rate of which must be controlled.

With such a finely-tuned system, there are a lot of different things that can go wrong. These problems are what can cause bulbs to fail to ignite or to flicker when they're running.

Basic Troubleshooting Steps

Before you can identify the cause of HID failure, you should try some basic troubleshooting to attempt to narrow down the problem. Here are some different scenarios, and what you can do to troubleshoot them.

Troubleshooting Lights

1. Neither bulb functions. If both bulbs fail to work, any number of issues may be wrong, but it's unlikely to be the bulb or the ballast. It may be an issue with a central component, such as the wiring or the battery, or it may be a sign that it was incorrectly installed. 

2. One bulb functions, the other does not. In this instance, the battery and wiring are likely fine, though part of the wiring leading to one bulb may be faulty. It may also be a single ballast, igniter, or bulb. Try swapping the bulb from the good side to the bad and see if it works; if not, swap back and swap the ballast. Through trial and error, you can identify which component is faulty.

3. Your bulbs light inconsistently. If it takes effort, toggling between low and high beams, or turning your lights on and off to get them to light, you may have an issue with your battery, ground, wiring harness, switch, or another part of your system. The bulbs and ballasts are likely fine, but something common between them is not.

4. Your bulbs flicker. Flickering HIDs is a very common issue. It usually means that the bulbs are not getting consistently high, constant voltage. This can be a problem with the ballast, the connections, the wiring, or the battery. If only one bulb flickers, it may also be the bulb or ballast for that side. Through a process of elimination, you can narrow down the cause.

HID Lights at Night

5. Your bulbs are dim, off-colored, and flickering. This typically means that the bulb is not getting a consistent voltage. If it's just one bulb, it's likely the ballast or one of the connections in the wiring. If it's both bulbs, it may be the wiring harness or the battery.

6. Your bulbs are the incorrect size or design. There are four kinds of HIDs. D1 series bulbs have an igniter built into them. D2a bulbs need an external igniter. R bulbs are designed for reflector headlights, while S bulbs are designed for projectors. Make sure your kit has the right kind of bulb for your headlight enclosure.

Problems and Solutions for HID Issues

Now let's talk about the problems that can plague an HID installation. These are common with aftermarket kits, particularly if they're not designed, manufactured, or installed properly, but these issues can crop up with factory HIDs, not just aftermarket ones. Don't feel bad; while user error is a contributing factor, just about everything is fixable.

1. Your HID kit was poorly made. One of the biggest issues with HID kits is that they can be poorly manufactured to substandard quality, often from a factory in China. These HID kits might look fine on the outside, but inside, they have poor quality parts, poor connections, and poor engineering.

If you bought the cheapest kit in the market, it may be that you received a poor-quality kit with bad hardware. If your HIDs refuse to work, or if you have to turn them off and on several times to get them to ignite, you may have this issue.

Poor Quality HID Lights

Unfortunately, the solution to this is to get a higher-quality kit. We strongly recommend replacing a faulty kit, because a faulty kit can cause excess battery drain, a shock hazard, and can even start a fire

2. Your ballast is bad. Each HID bulb needs a ballast to power it. If one of your headlights works fine and the other does not, it's a possibility that the ballast is faulty. A faulty ballast may refuse to draw enough charge to ignite a lamp or might fail to keep up a consistent voltage to keep the bulb running.

To test this, swap in a known-good ballast (like the one from your other headlight) and see if it works. This will help you determine whether the ballast or the bulb is faulty, or if there's another issue somewhere in the wiring harness.

The solution to this is easy; replace the ballast. Ideally, the vendor you purchased your HID kit from will have a warranty or return policy you can use to exchange the ballast for a new one, once you determine that this is the issue.

3. Your bulb is bad. Bulbs can go bad in HIDs for many different reasons, but they all generally result in the same thing: the HID bulb ceases to work. In some rare instances, an HID bulb might be manufactured with a defect that prevents it from operating properly or from burning out prematurely.

Burned Bulb

More likely, though, the HID has been damaged, either in the installation or in use.

  • Water or moisture can corrode contacts, preventing proper and consistent voltage from reaching the bulb itself.
  • Defects or damage to the chassis of the bulb can cause a leak, letting out the Xenon and leaving the bulb non-functional.
  • Defects or damage can disrupt the electrical flow to the bulb, resulting in weak, pink/purple light, typically indicating a faulty bulb.

If you have a known good headlight, you can swap the bulb from one side to the other. If the bulb still fails, it's likely the bulb; the ballast worked fine for the other bulb, after all. 

Like with a faulty ballast, you will need to replace a faulty bulb. Ideally, your vendor will have a return policy and will swap it out for you. Otherwise, you may need to purchase a new bulb.

4. Your HID was installed incorrectly. One of the most common issues with HID systems is improper installation. The bulb, the ballast, and the wiring all need to be firmly and tightly installed, and hidden from moisture. HIDs also need to be grounded properly to function correctly, and improper grounding is a common installation error.

The best way to diagnose this problem is if you're having inconsistent issues. One light works fine and the other doesn't, but which one is faulty changes from time to time. You may have trouble getting them to ignite one night, but no trouble the next. They may be flickery, particularly in usage circumstances such as using the car alarm. 

If this is happening, go through the installation instructions and double-check everything. Make sure the bulb is firmly seated, the igniter is firmly connected, and the ballast is firmly connected. Make sure there are no cracks, cuts, or issues with the wiring. Make sure it's appropriately connected to your battery and grounded. Run through the entire process for each light. Ideally, you'll find a mistake you made and can correct it.

Repairing Wiring

5. Your wiring is failing. This one is a common issue with aftermarket upgrades on older vehicles. Every part of a vehicle decays over time, from the breaks to the radiator to the hinges. Entropy is a cruel fact of life, after all. Your wiring harness is no different. Many things can go wrong with your wiring, including constant wear making the insulation brittle and break, flexing leading to the wires breaking, or the connections to your newer components slipping or breaking loose.

Usually, when wiring fails, it breaks and no longer works. Sometimes, though, minor, almost invisible damage can cause faults that are difficult to diagnose. It can even be as inconsistent as depending on ambient temperature and humidity. 

Your fix for this issue is to replace whatever parts of your wiring harness are failing. Unfortunately, this can be difficult enough to find that it's often better to replace the wiring entirely.

6. Your battery is failing. HIDs draw on power from the battery to ignite and to keep running. That power is filtered and stored by the ballast, but the battery needs to be able to provide that power for the ballast to function properly. If your issue seems to be the ballast, but it's inconsistent, you may have a battery that is slowly dying.

If your HIDs flicker or make a clicking noise, your car's battery may have a low charge and is unable to maintain the voltage necessary to keep the HID running. 

Thankfully, any auto parts store will be able to test your battery for you and provide you with a new one quite easily. If it's still good, you can throw it on their charger for a few hours to bring it back up to a full charge. If your battery is drained but still perfectly good, you may want to have your alternator tested while you're at the auto parts store.

Blown Fuse

7. Your fuses have blown. If your HIDs light up but then shut off unexpectedly, you may want to check your vehicle's fuses to see if they are blown. Many vehicles come with 10- or 20-amp fuses, but HIDs are best used with 30-amp fuses. You may wish to consult with your owner's manual to make sure that a higher amperage fuse will not damage another component, though they are usually safe.

8. Your bulbs don't fit. Another common issue is purchasing an HID kit that isn't compatible or doesn't fit with your vehicle. There are thousands of different makes and models on the road, and there are subtle differences between even the same make and model in different years. You should use a vehicle search site to verify what bulb types fit your vehicle, and order a kit made for that vehicle type.

HIDs can be a bit of a pain to troubleshoot when they go wrong, but there's almost always a single, definite cause for the issues you're experiencing. Just try to work from the endpoints in; test to make sure the bulbs are fine, then the igniters, then the ballasts. Test to make sure every connection is tight and waterproof, then test for faults in the wiring harness. Check to make sure the battery holds a charge and isn't old or faulty. If all else fails, consider switching to LEDs instead.

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LED LightStreet