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...

 

[WolfDampf]

Swapping back to stock halogen bulbs did not fix the issue.... I'll have to do some more digging. Both videos I have my headlights set to on

LEDs:

View: https://youtu.be/SnTTFKbZ0KA?si=KlWVAbN2_w2k8LSc


Halogens:

View: https://youtu.be/pYhQ4QQOcVQ?si=Wq6zlRSrmJLmQpsO

 

[WolfDampf]

I pulled every fuse under the engine bay and inside the glove box and nothing was blown

 

[WolfDampf]

Headlights on they're supposed to be dimly on and get full bright with brakes. Instead it's full bright at all times. Third brake light functions fine. With headlights off the side lights activate with brakes and deactivate with no brakes just fine as well.

 

[XR650R]

Might be the brake light switch. Worth a look.

View: https://www.youtube.com/watch?v=QEZUwMXFmtc

 

[WolfDampf]

Might be the brake light switch. Worth a look.

View: https://www.youtube.com/watch?v=QEZUwMXFmtc

I'll take a look but wouldn't my third brake light be non functional if the switch was bad?

 

[Intuit]

Might be the brake light switch. Worth a look.

What's odd about that theory is he's able to selectively activate his high-mount by pressing the brake.

Looking at the circuit diagram for my 2016 (posted above), it doesn't make sense.
They're all on the same Blue-Gray identified as CCA26.
Only thing that would make any sense, is if the LEDs damaged the socket in a way that allows the marker light voltage to cross-over to the brake light.
To rule that possibility out, turn off your marker lights.
If the brake lights switch with the marker lights, there's the answer; damaged sockets.

 

[Intuit]

https://www.autozone.com/electrical...-3157st/232887_0_0?searchText=tail+light+bulb

Been awhile since I had the stock tail. Had to look it up. The previous motorcycle had a similar type of bulb base on the turn sigs. (single filament instead of dual) The base on the replacement LEDs were all too thick. If I forced them in, it would damage the socket by pushing/pulling the contacts in/out with the bulb. (very nearly did) Tried a few different LEDs but they were all the same; fit was too tight. I ended up shaving down the base from the original set of LED I bought. I theorized that the motorcycle socket was a higher tolerance because they would vibrate loose from the socket otherwise. (solid engine mounts)

 

[XR650R]

I'll take a look but wouldn't my third brake light be non functional if the switch was bad?

Yeah. Good point. It's not the switch, then.
As Intuit implies, it may be the fit.
But, that doesn't account for the fact that you put the stockers back in and it still did the same thing.
I think something got bent.

 

[WolfDampf]

What's odd about that theory is he's able to selectively activate his high-mount by pressing the brake.

Looking at the circuit diagram for my 2016 (posted above), it doesn't make sense.
They're all on the same Blue-Gray identified as CCA26.
Only thing that would make any sense, is if the LEDs damaged the socket in a way that allows the marker light voltage to cross-over to the brake light.
To rule that possibility out, turn off your marker lights.
If the brake lights switch with the marker lights, there's the answer; damaged sockets.

1st pic is what it looks like with brake on markers off. 2nd pic is markers on. So the marker lights and brake lights have been switched. Not sure how to fix this. I've tried flipping the bulb and no fix.

 

[WolfDampf]

So as the first pic shows my brake lights are dim. The 2nd pic just marker lights on brakes released it's bright. Filaments have been switched. Not sure what would cause that? The socket seems fine I guess but not sure. I guess I'll try changing the harness and see...

 

[WolfDampf]

All issues fixed! I found it was the wiring. The brake wire and marker wire were reversed a simple swap fixed the issues.

 

[Intuit]

All issues fixed! I found it was the wiring. The brake wire and marker wire were reversed a simple swap fixed the issues.

Did someone attempt to re-pin the harness? How or why did they get switched around?

 

[WolfDampf]

Did someone attempt to re-pin the harness? How or why did they get switched around?

My body shop done a lot of shady work and I had to bring it back multiple times to get it all fixed and it still wasn't addressed.... One example being the drain hose below the vent being disconnected and then plugged up with a goop of rubber stuff after I asked why the holes that are taped from factory were not retaped as I asked in the first place... Which lead to water backing up and even more water inside my cabin. Then my bumper being riveted on instead of replacing the bumper clips because he "didn't know if I wanted to pay for new bumper clips or not" even though I gave my number and said to ask questions before doing any work... Now my bumper needs rivets due to the holes on the sides and they gotta be drilled out and replaced every time I remove the bumper 🙄. Then the tail light bulbs just dangling inside the housings and the tail lamp assembly not sitting flush due to the bulbs being left there and jammed in ruined the rubber grommets for the screws and that was when I came to pick up the car. The paint was also scuffed up and scratched/chipping the day I picked it up....

This however the brake light issue was my fault 😂. I swapped my tail light assembly for one off the 2013 Hatchback as I like the style and had to rewire for the new assembly sockets. I was so sure I did them right, even double checked but I guess I was THAT sleep deprived that night I did it... I assumed it was more of the body shops shenanigans as they also messed with that harness when they moved it for the repair and left my interior dirty. Thankfully it was a simple fix one I could perform and was quickly pointed out by Intuit mentioning the filament check. Thanks everyone!

 

[Intuit]

To be a paid professional and doing "work" like that is super incompetent. It's people like them that make folks sell/junk their vehicles long before their time. Some nitwit hit & run or did you back into something? 🙂