Tail lights stuck on full brake light

[WolfDampf]

2014 Fiesta ST. I recently installed some LED bulbs for my tail lights and everything was working fine until I brought the car into my body shop to get some body work done. Since then I've been having an issue where the side lights stay on full brightness all the time. Third brake light works fine, side lights stay on full brightness whether I'm braking or not. Not sure where to look if this is a fuse issue? I'll be checking fuses when I get an off day but wanted to post for other things to check. Thanks a lot everyone!

View: https://youtu.be/MIWIZYEeuVE?si=HYPHjxNcLLx81qHN

 

[Intuit]

If you reinstall your stock bulbs, does the issue persist?

If not, your LED bulb type is incorrect. (the pins are wired different)

Since your high-mount works as intended and the tail lights STAY lit, the only (likely) possibility is issue with LED. Issues with BCM or wiring, the BCM will set code(s) which can be read.

 

[XR650R]

Agree with Intuit. Change back to the stock bulbs, and see if that solves the problem. If it does, it's your LEDs.
I put LEDs in mine and they work fine. I'll try to see what I bought, exactly.

 

[WolfDampf]

If you reinstall your stock bulbs, does the issue persist?

If not, your LED bulb type is incorrect. (the pins are wired different)

Since your high-mount works as intended and the tail lights STAY lit, the only (likely) possibility is issue with LED. Issues with BCM or wiring, the BCM will set code(s) which can be read.

View attachment 64925

View attachment 64926

Thanks! I'll check if that's the issue, but they did work fine for the first few weeks I had them installed which is what makes me wonder if something broke.

 

[Intuit]

It's normal for the marker lights to be temporarily on though, it's not necessarily noticed during the daytime.

If you turn on your headlights during the day (rather than wait for nighttime in auto mode) and see your brake lights come on, you have confirmed that the LEDs are shorting; activating marker lights with brake lights.

 

[WolfDampf]

It's normal for the marker lights to be temporarily on though, it's not necessarily noticed during the daytime.

If you turn on your headlights during the day (rather than wait for nighttime in auto mode) and see your brake lights come on, you have confirmed that the LEDs are shorting; activating marker lights with brake lights.

I'll post a night video when I get a chance that's when it's easily seen. When my headlights are on the marker lights are super bright, and when brakes are applied third brake light activates and the marker lights do not change brightness at all. Everything was working correctly when I first installed the LEDs and I've tried changing to new different brand LEDs since the issue started and it hasn't fixed it. I'll revert to stock bulbs next and see...