Aftermarket third brake light

[KChurch86]

Well, I finally got around to mounting an aftermarket third brake light since my spare tire now obstructs the OE one, which is as illegal as it is dangerous. I had planned on splicing into the trailer wiring harness for power, then realized that the 4 flat wiring has no brake light function...

Those of you with added third brake lights, where and how did you splice into your wiring to power your light? I'm searching for ideas here.

 

[Prime]

I did a tap splice into the wire that goes to the drivers side brake light. When I routed all of my wires down from the rack they were all dropping in the boot at the drivers side rear. So it was the logical place to grab brake signal.

 

[KChurch86]

I did a tap splice into the wire that goes to the drivers side brake light. When I routed all of my wires down from the rack they were all dropping in the boot at the drivers side rear. So it was the logical place to grab brake signal.

Did you pick up a negative wire somewhere too, or just ground to the body? I was thinking of going this route as I've got my wires running in on the right-side of the bumper next to the plastic corner; so they're pretty much right under the passenger-side taillight already.

 

[Prime]

The tail lights are grounded to a 10mm bolt right behind each one. So you can just grab ground there.

 

[KChurch86]

Nice, thanks man. I'm gonna see if I can bang this out real quick while I grill up some dinner.

Thanks for the help.

EDIT: Nope, never mind. I'll put it off until I have a little more time.

 

[KChurch86]

I see no bolt/ground behind either tail light.

No worries, I'll add one.

 

[Prime]

When I say behind the light I man under the trim in the trunk area.

 

[Prime]

Passenger side, pull the lower trim, bolt is about 1.5" up from the bottom right where the metal turns for the back.

 

[KChurch86]

I mean, you seem very sure of yourself, buuut...

No worries, I located the brake signal wire (solid green, no stripe) and tested with a body ground. All good.

Then I drilled a hole

and removed the paint from around it, then re-tested with this new ground. Still good.

 

[Muadeeb]

The ground is inside the cargo area, behind the lower panels there.

 

[KChurch86]

Oooh, you mean there's an INSIDE?

Derp, mah bad.

/Yeah I'm not pulling the interior panel at this point.
//Light is already wired, started to clean up

 

[Prime]

Learn to read, Kyle!

 

[KChurch86]

Learn to read, Kyle!

Learn to deal with my ineptitude, Jay!

 

[Muadeeb]

Oooh, you mean there's an INSIDE?

Derp, mah bad.

/Yeah I'm not pulling the interior panel at this point.
//Light is already wired, started to clean up

Not acceptable. Rip apart all the things.

 

[J Everett]

To go all the way back to the first post, the flat four wiring for a trailer has brake light functions. You HAVE to have brake lights on a trailer. The green and yellow wires are for both brakes and turn signals (green = right turn/brake, yellow = left turn/brake, brown = running lights, white = ground). The problem with using that for a third brake light is that it would flash anytime you used the turn signal. So you were still right to skip that route and tie into your actual brake light wire on the truck itself. I just wanted anyone else who stumbles across this six months from now, or whenever, to have more of an idea of how and why to do what you did.

 

[KChurch86]

To go all the way back to the first post, the flat four wiring for a trailer has brake light functions. You HAVE to have brake lights on a trailer. The green and yellow wires are for both brakes and turn signals (green = right turn/brake, yellow = left turn/brake, brown = running lights, white = ground). The problem with using that for a third brake light is that it would flash anytime you used the turn signal. So you were still right to skip that route and tie into your actual brake light wire on the truck itself. I just wanted anyone else who stumbles across this six months from now, or whenever, to have more of an idea of how and why to do what you did.

Thank you for that needed clarification, I was lazy and didn't get into all that at the time. I guess I meant that the 4 flat harness has no DEDICATED brake signal.

Thanks again.