Leer Topper - Third Brake Light Wiring help

[zatiny8sv]

Hi guys,

Purchased a used RAM and put a LEER 100XL Canopy on it. Was planning on connecting the Third brake light and did my research and learned that I needed to connect the red wire from the canopy to the white with brown stripe wire underneath the bed, and ground the black wire from the canopy -- easy peasy.

Well, when I removed the taillight I noticed that the previous owner already had some sort of wiring harness installed. I traced the wires:

A: Comes from the White w Brown stripe wire
B: Goes to the Trailer Connector
C: Comes off the Taillight bulb

.....I'm terrible with electronics, so wanted to ask you guys:

1. Where do i connect the Red wire from the canopy, now?
2. Do these existing harnesses make it possible for me to easily connect the dome light from the canopy, as well (instead of running a wire from the battery for constant power)

Appreciate the help, Thanks!

 

[zatiny8sv]

Anybody....

 

[crash68]

1. Where do i connect the Red wire from the canopy, now?
2. Do these existing harnesses make it possible for me to easily connect the dome light from the canopy, as well (instead of running a wire from the battery for constant power)

Use the white/brown(I think it's actually white/purple) under the truck for the third brake light on your cap.
You can use the +12V from the trailer 7 pin plug, I'm guessing it's for the lighting in the cap. If the previous owner tapped the trailer +12V, use that one. I would get rid of the rest of that added wiring.

 

[zatiny8sv]

Thanks, Crash!

So.....wire A, since it’s connected to the white/purple wire.....I should be able to tap into the red wire A (where I have the electrical tape in the first picture), right?

And then if wire B is in fact connected to the 12V wire from the trailer 7 pin plug, I should be able to connect the canopy’s interior light tot that wire, after the in-line fuse, right?

 

[crash68]

If that what those wires go to, run with it. I'm not a fan of those wire connectors, I'll usually solder mine. Make a good ground to the body for the cap wiring. You may want to put some sort of miles plug arrangement(similar to that white plug you have now) so if you want to remove the cap, you can unplug the wiring.
The Leer cap on my truck actually has a little fuse block with a plug in wiring harness. It also has a power lock that wired to the tailgate lock.
I also added some LED tape lights to the top.

 

[tigerl0128]

Use the white/brown(I think it's actually white/purple) under the truck for the third brake light on your cap.
You can use the +12V from the trailer 7 pin plug, I'm guessing it's for the lighting in the cap. If the previous owner tapped the trailer +12V, use that one. I would get rid of the rest of that added wiring.

This may be a stupid question but I have no power to that white and purple wire so how do I go about finding out why?

 

[crash68]

This may be a stupid question but I have no power to that white and purple wire so how do I go about finding out why?

It would only be a stupid question if you didn't ask it.
That Wht/Pur wire only powers up when you apply the brakes. Where and how that is powered up I'm not sure. It probably comes from the BCM, possibly the same output that is used for the third brake light on the top of the cab.
You would probably need to find a wiring diagram to trace out that wire.

 

[Gero]

Did you ever find out how to get power from the white/purple wire? It doesn't power even if the brakes are depressed. Is there separte a fuse for that?

 

[jawzs2]

Did you ever find out how to get power from the white/purple wire? It doesn't power even if the brakes are depressed. Is there separte a fuse for that?

Pretty sure you need to have the key on also, at least my 2014 is that way

 

[crash68]

Pretty sure you need to have the key on also, at least my 2014 is that way

Strange as my '15 works without the key on. Brake lights by design are supposed to work wether the vehicle is running/on or not.

 

[Gero]

I couldn't get any power. Key or off, ended up tapping the wire for the bulb on the driver side tail light.

Now I gotta figure out where to get a constant 12v for the dome light in the cap. Any suggestions? Tapping into the 7pin trailer harness is an option...does anyone know the wire color?

 

[Gero]

Well, I realize I can't tap the drive side tails brake light because the cap light will blink when I signal right.

 

[turkeybird56]

Here U go.

 

[Mav3rick]

Does anyone have pictures of how they wired in the interior dome lights for the leer truck caps, bought my cap used purchased the TAG wiring harness on Amazon which has the red white and black wires in the nice housing, found the white and brown/purple wire under the truck for the third brake light the black is the ground which I’ve got a plan for picking up ground in drivers side brake light just trying to figure out the last piece of the puzzle the red wire for the additional dome lighting, previous owner also added in a 12v fan to this truck cap so that’s the other reason I need to find a good 12v connection to tie into? Any easy suggestions or parts to buy to make it simple?

 

[MyNewRam]

FWIW, I just replaced my 3rd brake light(on the topper) and it wasn’t working. The previous owner had it wired into both brake lights and some type of solenoid under the bumper.

I did a little research and turns out that under the truck, left side of the spare tire, there’s a wire harness with a white/purple wire sticking out of it. That is the line for the topper brake light.

Wired it up, correctly, and it works perfect! I also ran the wiring up behind the left tail light and grounded it there.

 

[GTyankee]

The pigtail for the Camper Shell Lights ,
Begins at the Main Harness at the Drivers Side Rear Wheel

The Electrical Connector for the Tailgate is fairly close to it,
another Electrical Connector for the Tailgate is behind the License Plate

I don't have a better image