When LED light bulbs were invented, it was assumed they would replace all standard filament bulbs rather quickly. However, most of the cars, trucks, and SUVs driving down the roads of America still have standard light bulbs inside the trunk of their vehicles. This component often goes overlooked in regards to routine service and maintenance, but without it, trying to find items inside the truck, both in day and night, would be extremely difficult.

What is the truck light bulb?

Simply put, the trunk light bulb is the standard, small light bulb that is located on the top portion of your car's trunk. It comes on when the trunk hood or lid is opened and activated by a series of relay switches that supplies power to this component only when the trunk is open. Due to this fact, the trunk light bulb is one of those rare bulbs that can last for years, since it is rarely used. However, like any standard light bulb, it is susceptible to breaking or wearing out due to age or in some cases, due to bumps that can break the filament inside.

It's pretty easy to know when the trunk light bulb is damaged and needs to be replaced; however, there are a few common warning signs that might alert the driver of the vehicle that a potential issue with this component is approaching, so they can be proactive and have it replaced before it burns out.

Noted below are a few of the common warning signs that a problem with the trunk light bulb exists and should be replaced by a knowledgeable mechanic.

Light bulb is dimmer than normal

A standard light bulb is illuminated when electricity is sent through the light bulb. The electrical signal flows through the bulb and a series of electrical filaments light up as the power is circulated through the bulb. In some cases, these filaments might begin to wear out, which can cause the light bulb to burn much dimmer than it normally does. Although most car owners don't pay attention to the exact brightness of their trunk light bulb, this warning sign is pretty easy to notice. If you open your trunk and the light is burning dimmer than it usually does, take the proactive step to remove and replace the trunk light bulb or contact a local ASE certified mechanic who can complete this project for you.

Light bulb burns brighter than normal

On the opposite side of the equation, in some situations the light bulb will burn brighter than usual if it is starting to wear out. This is again due to the inconsistent flow of electricity inside the bulb when the filaments are brittle, damaged, or are beginning to break. Like the situation above, there are two things you can do:

  • First, replace the light bulb yourself, which is not too difficult depending on what type of vehicle you own and your comfort level removing a cover from the trunk lid.
  • Second, contact a mechanic to replace the light bulb for you. This might be a good idea if you have a newer vehicle where the trunk light bulb is contained inside the trunk lid and is difficult to access. An experienced mechanic will have the right tools available to complete this job.

The trunk light bulb is one of the most inexpensive auto parts to purchase, and one of the easiest to replace on most vehicles manufactured prior to 2000. If you have noticed that your trunk light bulb is burning dimmer or brighter than normal, or if the light bulb has burnt out, contact one of our professional mechanics who can replace your trunk light bulb for you.

This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Trunk Light Bulb and was authored by Timothy Charlet.

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