One of the most annoying situations is being pulled over by a police officer due to a burnt out tail light. However, even more frustrating is calling the insurance company after you've been rear-ended by another motorist because they didn't see brakes lights due to a burnt out $2.00 part. The tail lamp bulbs are arguably the most important yet least expensive parts on any car, truck, or SUV that can have a huge impact on our daily lives. It is for this reason among others, that being able to identify a problem with your tail light bulb and repair it as soon as possible is more important than you might have previously assumed.
The tail light bulb on most of today's modern cars, trucks, and SUVs operates the tail light and brake light. On many vehicles, these two independent lights are triggered by different light bulbs, but it's becoming more common that both applications are illuminated by one, multi-filtered bulb. They are activated when the headlights switch is engaged, in either the parking or headlight mode. Due to the frequent use, light bulbs do have a lifespan which means they need to be replaced occasionally. Most ASE certified mechanics subscribe to the philosophy of replacing all tail lamp bulbs at the same time.
Noted below are a few of the symptoms of a bad or failing lamp bulb. If you notice any of these, make sure to replace your tail lamp bulbs as soon as possible.
Tail lights do not work when the headlight switch is activated
As noted above, different automotive manufacturers have different tail lamp bulb configurations. In many cases when the lights don't work when the headlight is turned on, it is caused by a burnt out or short circuited tail lamp bulb. Unfortunately, this is often not discovered until a police officer or somebody else informs you of this problem. A good rule of thumb is to check this once per week. Simple turn on your headlights, walk to the rear of your vehicle and ensure that both lights are active and illuminating. If you notice that one or both are burnt out, replace them with the recommended lamp bulb or have an ASE certified mechanic complete this work for you.
Brake light doesn't work when brakes are applied
The tail lamp bulb can also trigger the rear brake lights as well. This item is very difficult for the individual to inspect, but it is always a good idea to have somebody help you complete this important safety inspection. As noted above, once per week, take a few minutes during your day or evening to check if all brake lights are working. If the parking lights work (meaning the rear lights that turn on when the headlights are active), but when pressing the brake light the light does not work, have the tail lamp bulb replaced.
A common issue people have is when the parking lights work, but when the brakes are pressed, the tail lamp bulb turns off completely. This is sometimes caused by a short in the tail light system or a fuse. Either way, if you notice this problem, have an ASE certified mechanic inspect and replace it as soon as possible to avoid any safety or legal issues with the police.
Set up routine service for lamp bulb replacement
Since it's nearly impossible to diagnose a lamp bulb before it has burnt out, a good safety rule is to set up an annual or bi-annual period to replace them. Many people have the tail lamp bulbs replaced every other oil change, during tire replacement or when they have their air conditioning serviced. A crack in the tail lamp lens might also cause the rear lights to malfunction. Any of these maintenance check-ups are great times to be proactive about replacing the tail lamp lens or bulbs – even if they are not due for replacement.
Tail lamp bulbs are vital to the safe operation of your vehicle. Taking time and investing $10.00 once per year to ensure your tail lights don't fail you not only can protect you and others riding in your car, truck, or SUV, but can also reduce the potential of being pulled over and cited by law enforcement.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Tail Lamp Bulb and was authored by Timothy Charlet.