Why Do Bulbs Go Bad?

Tail light bulb(s) replacement

Changing bulbs is simple, but why do they go bad in the first place? Unlike light bulbs in your house, those in your car live a rough life, exposed to heat, cold, vibration, and bumps. Plus, automotive lights quickly cycle on and off, which is harder on them than being constantly on.

Recently, auto makers have moved to bright, long lasting, LED (light emitting diode) tail, brake, and indicator lights, so your current car may be the last one that ever burns out a light bulb.

Until then, at least changing them is easy. This task requires no experience, only basic tools, and shouldn't take more than a few minutes, depending on your model.

Every car is different, so find your manual for the full instructions…

When To Change Your Taillight Bulbs

“You also risk being pulled over by the police and face a possible fine”

With age, the quality and quantity of light from a bulb diminishes, plus corrosion on the contacts can cause it to dim. You should check that all your vehicle's lights function properly every few months. A dim bulb may be rectified by cleaning the socket and bulb contacts, or replacing the bulb.

There is seldom need to change a bulb before it blows, but change a blown bulb as soon as you notice it. Other drivers rely on your lights to see you and judge distance at night.

All vehicles are different, so if it is time to change a bulb, use our before you begin checklist, and find your car for specific instructions.

How To Change Your Taillight Bulbs

This video is a general guide. Find specific step by step instructions in the manual.

A very brief summary of the task for the typical vehicle. Your Haynes manual will have specific details:

  1. Examine the rear of the vehicle for visible screws in the taillights. Remove them if present and skip to step 6.
  2. Open the trunk or hatch to access the rear of the taillight cluster. You may have to remove trim or carpet to reach it.
  3. Remove screws, wingnuts, or clips holding lights to car. 
  4. Remove the assembly and locate the blown bulb.
  5. Remove the bulb socket, usually by twisting counterclockwise.
  6. Push and turn bulb to remove, or on some bulbs, pull straight out. Install new bulb.
  7. Reinstall the bulb socket, and housing.
  8. Replace trim or lens.


Even one blown tail or brake light bulb can greatly increase your chance of getting rear ended.

Why You Should Change a Blown Bulb ASAP

Having a taillight, brake light, or turn signal bulb blown out greatly increases your risk of being hit. Of course, you also risk being pulled over by the police and a possible fine.

Cars have a pair of taillights (or more) so the driver behind can judge distance and closing speed.If the rear of your car isn't clearly visible at night, you risk being hit by a following car. The same applies to the brake lights at any time of the day.

Turn signals are necessary for safety sake to signal your intention to other drivers before turning or changing lanes.

So, it’s imperative that you change blown bulb(s) as soon as possible. Considering how cheap bulbs are, and how little time it’ll take you to replace them, there is no reason not to.

Before You Begin

Tools you will need

Only basic tools are required for this job on most cars.

  • Flat screwdriver
  • Phillips screwdriver
  • Paper towel/gloves
  • Ratchet and socket set

Parts you may need

  • Bulbs


Make sure you have the correct type of bulb and wattage.