There’s a ton of upside in converting from traditional incandescent bulbs to LEDs, and one of the biggest is reduced strain on your wiring harness thanks to less current draw.

But there’s one spot where that lower power demand can become a problem—your turn signals. And to understand why, let’s explain (in very basic terms) how a typical turn signal flasher relay works.

Most automobiles, particularly vintage ones, use a flasher relay that relies on a specific amount of resistance to operate. When you energize your turn signal, the electricity that will eventually illuminate the bulb first generates heat in the bimetallic element inside your flasher relay.

After a moment, that heat temporarily deforms those bimetallic element so that, when it gets hot enough, it pulls away to make electrical contact in the turn signal circuit. When that happens, your turn signal turns on. A split second later, the element cools down to the original shape and the circuit is broken—your turn signal turns off and the cycle repeats until your turn signal is switched back on. (That process also explains why you hear that telltale click-click-click noise as the circuit repeatedly opens and closes.)

It’s a delightfully simple design that’s been used for decades.

But remember, LEDs typically draw a heck of a lot less current than a traditional incandescent bulb. So when you simply take the old incandescent bulb out and pop a modern LED in its place, it means that tiny metal strip is seeing less current and, may not get hot enough to make the circuit of your original flasher relay.

Then end result is an LED turn signal that doesn’t blink—it just stays lit until you turn it off.

That’s why the folks at American Autowire offer a turn signal flasher relay specifically designed to work with LED bulbs. And better yet, converting to the LED-friendly turn signal flasher is as simple as pulling the old one out and plugging this new one in.

You can learn more about the entire process (and the turn signal flasher solution) in this quick, informative video from American Autowire.

If you’re struggling with LED turn signals bulbs that won’t flash, this video will show you why:

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