Third Brake Light for Camper/Topper

[Harry S. Stamper]

I've seen lots of different options on wiring up the third brake light on a truck topper and figured I'd share what I did on my 2014 Silverado. I wanted to wire it directly without messing with logic boxes (lots of people have issues with them), running a wire all the way to the fuse box, or buying a $100 harness. Basically followed what the guy in the thread below did.

 

 

I wasn't reading the pinout diagram correctly at first and incorrectly tapped into pin 28 (it's a purple and white wire). Pin 13 (purple and gray wire) is actually on the top row of the connector when plugged into the X63A junction box. To get to the wire I cut back some of the protective wrapping and cut off the zip tie to loosen up the harness. There's not a ton of room to work but it's not too bad. There's a ground screw on the frame crossmember right next to the junction box. 30 minute job if I had to do it again, most of that being removing the spare tire and cutting back the wrapping.

 

Wire harness for Leer topper: https://truckoutfittersplus.com/truck_topper_parts/Topper-Wiring-Harness/Topper-Fuse-Box-Wire-Harness-only.html

3M Skotchlok wire taps. Highly recommended for easy wire tapping: https://www.amazon.com/gp/product/B0711LR1G4/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Pin diagram for the connector on the junction box: https://www.gmupfitter.com/wp-content/uploads/2021/05/UI-Bulletin_113c.pdf

 

[pokismoki]

my camper deosn't use the third brake light, left it disconnected, one less wire to short out I guess, no trouble from the Law either, so I skipped it..

[Harry S. Stamper]

2 minutes ago, pokismoki said:

my camper deosn't use the third brake light, left it disconnected, one less wire to short out I guess, no trouble from the Law either, so I skipped it..

Ha, I’ve been driving around without it for months and haven’t had any issues. Was doing some other work on the truck and got some motivation to finally wire it up