Brake lights not working

Hello, I'm Danny.

I've attached an exterior lighting wiring diagram below for your Sonata. I've cut the picture in half so you can view larger. Here is a tutorial showing how to check wiring:

https://www.2carpros.com/articles/how-to-check-wiring

The first thing I recommend is to check all grounds for a proper connection. Check for frayed, melted, corroded, exposed, or an otherwise bad connection. Let us know what you find. Hope this helps and thanks for using 2CarPros. Happy Holidays.

Based on the wiring diagram it looks like the first place to look would be the joint connector under the left front seat. That is where the power splits to the high mount brake light and to the stop lights.

Hello again.

Yes, I would check all the grounds as a start. Keep us updated and let us know what you find. Hope this helps and thanks again for using 2CarPros. Happy Holidays.

Danny-

Well, check this out: Traced the power and had power to the stop lights pulled bulbs and found the connection inside was dirty. Clean bulb connections and harness connector. All working now. Just a coincidence that the brake light switch went out and when it was replaced the dirty stop light connections showed up. Thanks

You're welcome!

Glad to hear you got it fixed. Thanks again for using 2CarPros and we hope you will use our site again in the future. Happy New Year.

Danny-