Car Series: How to tell if your turn signal bulb has burnt out

Today’s car series post is on how to tell if your turn signal bulb has burnt out, which is a very important, potentially life or death situation. I’m not kidding. I don’t want you to die.

two twenty one car series

Let me begin with a true story. One evening, a couple months ago, Brad and I ran into our next door neighbor while leaving to take Jack on a walk. She mentioned how her husband was out of town, and she was going to go to a local mechanic to have her tail lights looked at because they weren’t working. Brad and I said we would check it out for her, so Brad jumped in the car and we did the usual tests (I’ll show you below) to see what was going on. Turns out both of her back turn signal bulbs were burnt out. But it doesn’t end there. Since her car has a single bulb system this also meant that her tail lights were also out. So when she was braking her rear brake lights weren’t coming on at all, which is super dangerous. Think about it, you’re on the interstate, going 70 mph, and the car in front of you slams on their brakes. You slam on your brakes, but since your bulbs are burnt out your brake lights never come on so the car or semi-truck behind you doesn’t realize you’re braking until it’s too late. I mean really, who wants to die over a burnt out light bulb? Not I.

But there’s a way to tell if you turn signal/brake light bulb is going out or has burnt out completely. After we told our neighbor this she said she had noticed the warning and said something to her husband about it, but he brushed her off and said not to worry about it. Big mistake.

how to tell if your turn signal bulb has burnt out

Let’s start with the basics here. In many newer cars there is one light bulb per tail light. There are two filaments in each light bulb. One is for your brake light and one is for your turn signal. So when you’re stopped with your turn signal on one filament stays on while the other blinks. Get it? So when this bulb burns out it elimnates your turn signal AND brake light.

Now, how can you tell if a bulb (either in the front or rear of the car) is going out or has burnt out? The first indication is the speed of your turn signal in your car. You know– the click-click-click sound and the flashing light on your dashboard.

Luckily for me, when Brad’s parents came to visit this past weekend they had a burnt out tail light/turn signal bulb so I was able to use their car as my model. (We replaced the bulb before they drove the 3 hours back to their house. Safety first.)

Here’s video of a normal functioning turn signal. (Seriously, watch the video. It’s only 6 seconds long.)

YouTube video

Here’s video of a turn signal that’s indicating a burnt out bulb. (If you skipped the video above you really need to watch this one.)

YouTube video

Notice how the turn signal speeds up, blinking and clicking faster than normal, when there’s a burnt out turn signal/brake light bulb?

Now we know that at least one of the two right turn signals is burnt out based on the turn signal icon on the dashboard. But is it the front or the rear bulb? Or is it both? Here’s a trick to find out:  Park your car in a safe location. Turn on your hazard lights. Walk around your car and see which light(s) isn’t/aren’t flashing. I didn’t walk around the car for the video because we knew it was the right rear tail light, but you can see what I’m talking about with the hazard lights test in the video below.

YouTube video

I’ll cover how to replace a turn signal/tail light bulb in the next car series installment. This is something you can easily do in your driveway in under 10 minutes.

I guess I should finish the story about our neighbor, huh? She went to a local auto parts store, bought two bulbs, came back, and Brad switched out the bulbs for her. Neighbors of the year right here.

Learn anything new today?
Any burnt out turn signal/brake light bulb stories to share?
Who didn’t know that the fast blinking turn signal meant you had a burnt out bulb?

Stalk away!

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  1. Changing my car’s headlights was the first thing my dad taught me about car maintenance. It’s one of those things I’m really glad to know!

  2. Chelsea, this is good to know. Thanks for the post and can’t wait for the next post.

  3. Thanks for the post – I happened to learn this one in college, including how easy it was to replace it versus taking the car in and paying an arm and a leg to do it for you. As a woman, I have to say it was an empowering moment once someone took the time to show me how. Glad you will be posting how to change it next.

  4. I learned this one from my dad. I was casually commenting about the weird new speed of my turn signals. He helped me change them. In my (now dead) Honda, it was a pain to get Bulbs in and out. I just changed my headlight in my new (to me) Toyota using the same guidelines and it was so much easier!!!

    The Hazard light tip is excellent though! I had to sit in the car and turn the signals on and off with someone else outside! Hazards are much easier!

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  7. would’ve been a cheap kill. i am glad nothing happened. seriously, we should stop delaying the replacement until “tomorrow”

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  10. this is false info, there is only 1 filament used for brake/turn signal. the other filiment is for the tail light.

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