Tapping into tail light to power camper shell’s 3rd brake light

Searched the forums but couldn’t find any confirmation for which wires to tap into for powering my ARE’s third brake light on my 18 Tundra. Pictured are the wires for main brake bulb on left tail light.

I need confirmation that the green wire is positive?

can I tap into the black/white wire for my ground or do I need to ground off to the frame with a screw, bolt etc?

 

This guy does great work making plug and play taps.

https://www.tundras.com/threads/plug-and-play-brake-taps.89274/

 

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Deleting this post to avoid confusion.

 

Isn't there an open wire down on 7 prong trailer plug for hooking up brake light ? You can just plug into , or was that for power only?

 

I’m not experiencing this issue. I tapped into the blue wire and my 3rd brake light on shell now only illuminates when I press the brake pedal.

 

UPDATE

Tapped into green originally due to false info given to me and I found my 3rd brake light was constantly on w headlights on. Tapped into blue wire and now my 3rd brake light only illuminates when I press brake pedal. Grounded via the black/white wire. Success.
I did also use a detachable prong connection (dont know proper term) so if I have to remove shell, I don’t have to un-splice my wiring. Pics attached.

 

not sure, I know leer sells a special harness that gives you multiple connections for accessories but it’s $110

 

Are you certain? Turn on the turn signal for the side you tapped into and then look at the 3rd brake light. Then press the brake with the turn signal still on. I may be wrong (hope I am actually), but I'm pretty sure that same wire is energized for both the turn signal and brake, so when the turn signal is on it's flashing.

I'm sure there is a wire in the truck somewhere that only energizes when the brakes are pushed because the truck has a 3rd brake light. I just wouldn't expect the manufacturer to waste money running that light to the back harness. Could be wrong.

 

I did exactly what you said. No issue with the 3rd brake light blinking with turn signal. The 3rd brake light is only illuminating (and staying illuminated) while the brake pedal is depressed (even with left turn signal on. (i tapped into left tail light)

Thanks

 

Appreciate this thread. I had it figured out on my old cap, but since replaced it, and have yet to connect the brake light on it. Sounds like a good project for this weekend.

 

I am doing this tomorrow. Glad to confirm I need to tap into the blue wire…thanks!

 

I stand corrected then.

Like most things I do, it looks like I did it the hard way!

I understand now I think. Looks like the turn signals have their own bulbs.

 

i know the feeling

 

This helped a lot, sometimes the wiring is different colors. I’ve posted pictures of my set up and the wire difference:
White/Black is the Ground
Solid Green is the Running Light
Green/White is the Brake Light