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

Good morning! So I finally wired my third brake light and now my truck won’t start. 2018 Dbl cab V6 TRD Offroad. I checked the fuses and none are blown. Truck brake lights worked after connecting yesterday but this morning it stopped and also have a see dealer message on dash. Anyone encounter this type of issue and have a solution?

sounds like un related problem

I’m pretty sure it’s related to the installation of the wiring to the third brake light but can’t figure it out.

I can think of a reason it would drain your battery

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Battery is fully charged.

Do you have an OBD2 scanner? The truck might be throwing a code that could help you pinpoint.

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Yes I do have one but it’s at home. Well from reading other forum post on taillights not working and starter button disabled as well as gear shifter. It is said that if tailights do not illuminate when brake pedal is pressed. That a fuse is most likely blown. I checked the 2 10 amp fuses labeled rear lamp L and R. But overlooked the one labeled STOP. Good news it’s that one that blown. I also disconnected the GFC third brake light from the truck wiring. Going to give it another go later today and pick up some extra fuses.

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Ah nice at least it’s something easy. Seems crazy that a single blown fuse can make the truck not start though. Definitely gonna start packing fuses in my recovery kit!

Yes this has happened to me. “stop” fuse was blowing every time I hit the brakes. Disconnected the GFC brake light and problem went away. Tried to replicate when I got home but couldn’t. I carry extra fuses now.

Do you have a push to start Taco? Also did you re connect the GFC third brake light?

Yes I have the push start feature. I did reconnect it when I got home but everything was normal.

Good to hear everything is normal. Picked up a 10 pack of fuses.

Still blowing fuses! Anyone else having this problem or is it just me? 10 amp Stop fuse keeps blowing out. Is there an alternative to wiring the GFC third brake light?

Sounds like maybe you’re either not grounded properly or one of your wires is getting pinched somewhere.

Have you seen @2ayne’s how to? How To: Wire 3rd Gen Tacoma 3rd Brake Light

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.