Help! Wired tail light to third brake light now truck won’t start

I’m going to go out on a limb and say the polarity is reversed in the light or at the wiring quick connector on the light cord.

Try putting a multimeter to the leads of the third brake light to check for continuity which is shouldn’t have.


@LostDblCab @2ayne

Was there a definitive answer to this? It sounds like a big issue; I am going to wire the 3rd brake light soon. I will be following @2ayne’s guide.

He never did reply back to let ya know.
I’m assuming at this point the truck burned to the ground with him in it.


That’s a fair assessment!

Possibly the culprit.

I have condensation too and mine is fine.

They are supposed to be waterproof.

This is the link Mike sent me. These are the lights they use."%2Bred&th=1

1 Like

Is the light both a running and brake light? Thanks

Just a brake light but I’m sure if you purchase one elsewhere it’ll have 3 wires. The GFC ones have 2 wires.

1 Like

try putting a 15amp fuse in there. It did the trick for me

1 Like

It did the truck for what ??? Can you explain please?

it was a solution for continuing to blow the fuse for the rear brake light

1 Like

Thank you so much for this thread.

I had jerry rigged my brakelight (broke the little plastic plug before installing), but it worked no problem. They had to undo it when they upgraded my hinges.

Just went to re-jerry rig it and suddenly lights went out and the engine would not turn over. My truck is in the garage which requires some maneuvering to get into = no way you’re gonna be able to push/pull that beast out to a tow truck without building some redirects.

Some serious indigestion was resolved after I found this thread and specifically the STOP fuse.

NOW the question is whether to rig it up again or just leave it off? I’m surprised that this isn’t a more frequent issue.

2021 Tundra brake light install fail
-attached GFC harness to taillight wires, no 3rd brake light function
-‘STOP’ fuse blown, truck immobilized
-hook 3rd brake light to separate battery to verify function and GFC harness immediately completely fried/melted. No 3rd brake light function.

Is it possible I attached harness to the wrong wires and blew the fuse and 3rd BL?

Looking at buying a plug n play from puppypunter on Tundra forum, anyone done this with a tundra?

Just a heads up. I recently purchased a replacement third brake light for my camper from GFC. I wired it exactly like my previous brake light and kept getting blown fuses every time I hit the brake. After the fourth blown fuse, I decided to strip off the protective sleeve from the wire harness to try and troubleshoot. GFC attaches an extension wire to the existing third brake wire. They solder the wires together then cover it with heat shrink. After I stripped off the heat shrink I noticed the positive and negative wires were actually soldered together, causing it to short out and blow the fuse. I ended up soldering new wires together and making sure they were separated and now the light functions properly.


Wow! Thank you for this heads up!!!

Do you have any pic of install of the 3rd brake light on your Tundra.I am picking up my camper in a week…Anything would help.Thanks

Easy resolved.Blue positive.Blk/white neg…Done.