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How to wire up Leer 100XQ on 2015 Silverado

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  • 8 months later...

Wiring 3rd Brake Light on Truck Bed Cap for 2015 Chevy Silverado

If you follow wiring harness feeding the 7-way trailer connector from the bumper up toward the spare tire and peel back the wire loom, you should be able to find an additional blue wire in the harness. The blue wire carries the 3rd brake lamp signal for your bed topper.

For the interior dome light, you can get 12 volt power from the black wire feeding the trailer connector. You'd want to install a switch on the circuit like part # PK34513.

One of the wires would be power, the other ground.  You could also call the topper manufacturer, and they'd be able to tell you.

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On 8/11/2017 at 10:37 PM, Bigsho69 said:

Ok, I am a new member and need some help. I have a 2015 Silverado LTZ Crew Midnight Edition and I just bought a Leer 100XQ. I was surprised to find out that the dealer for Leer did not hook up the electrical stuff which includes the lights, third brake light, and auto lock. I have looked at the instructions they provided and they are not very good. Does anyone have any detailed instructions or a link to a video of how to install this stuff? I hate to pay another few hundred bucks to get it installed when the dang topper was $2500 by itself. So basically I am looking for where on my 2015 Silverado to hook up the wires for the light, the hook up for the wires for the third brake light, and where to hook up the auto lock which is supposed to unlock when you unlock the door of the truck. Any help would be greatly appreciated. Thanks.



well the dealer can not legally install without wiring the 3rd brake light...that is a federal offense

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  • 2 months later...

I went the easy route. I stopped into Cap World and bought a T harness.


The used Leer 180 I just bought has an odd 4 flat coupler to connect the high mount and the interior dome lamp. The T harness I just bought has the necessary coupler/ connector in the kit.


First get the black red and white wires into the protective corrugated sleeve. Then use a pull string to fish the wires up through the stake pole. There is another, smaller hole that I chose to use but the stake hole should do. Do this before you connect the T coupler below so you dont wind up trying to fish live wire. Place the individual wires into the white coupler as indicated in the included instructions and connect to the coupler from the bed cap.


Get behind the bumper and squeeze in the metal tabs that hold the 7 pin trailer coupler. I used my hand on one side and a screw driver on the other clamp but be careful. Once the clamps are squeezed, push the 7 pin connector out of the bumper (away from the spare). Remove the little lock tab and separate the coupler from the harness (a pain in the a$$) and separate the harness from the coupler.


From under the bumper, connect the T harness in place between the coupler and the harness you just separated.


Zip tie everything nice and tight.


Dome light turns on with its switch, brake light turns on when I brake or activate the alarm.



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  • 2 weeks later...

Also, as someone who has an aversion against drilling into the roof as long as the truck is still under warranty and I'm making payments,  I'm tempted to place my rooftop lights at the creat of the Leer 180 instead. It does rise about 4 inches higher than my cab roof... I feel like it would be easier to install them there, and easier to mitigate any possible leakage if it did spring a leak.


Has anyone else done this or thought of it?

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  • 1 year later...
On 8/17/2017 at 8:44 PM, Bigsho69 said:



Here is the third brake light working FINALLY!!!! This was not an easy job to figure out with no help. Hopefully if someone gets stuck they can use what I did to help them get it installed. I wired a hot wire from under the dash to power the interior light of the topper, grounded the ground wire in the left taillight, then ran the wires for the auto lock mechanism. Everything works and I am pleased with being able to do it myself.

Hey Bigshot 69

today i followed your post while wiring up my 3rd brake light on my topper.

THANKS! You save me lots of time. Thank you for posting your experience . It really helped. 

Edited by Big Del
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