Wiring a Camper Shell Third Brake Light on a 2017 Chevrolet Silverado

Updated 08/05/2025 | Published 06/27/2017

Question:

I have a 2017 Silverado that Im putting my old topper on. I need to wire the center overhead brake light on the topper topper already has the light and it is wired. The truck has a signal control box or whatever mounted above the spare, i assume theres a simple plug and harness that can tap into that controller and then the rest is easy. Where do I locate that part?

asked by: Erik W

Expert Reply:

I've never heard of an actual third brake light connector on a camper shell to plug in on a truck and we don't carry any parts to do that. The light generally needs to be hardwired into the truck's brake light circuit.

The issue with this on your 2017 Chevrolet Silverado the brake light and turn signal circuits are combined on one wire. So if you just wire it in the camper shell's brake light will also flash with the turn signals. To solve this issue we recommend using a vehicle to vehicle adapter, like the Curt # C56196, that connects to your truck's combined wiring and separates the brake and turn signal circuits.

On the input side our truck's left turn and brake circuit gets spliced into the yellow wire, the right turn and brake circuit to the green wire, and the white is grounded. Then on the output side the red wire goes to the third brake light and the green and yellow wires are capped off and not used.

See the picture I've attached.

expert reply by: Charles S

click to enlarge

Neil S.

11/2/2021

Hi and i just installed a leer topper on my 2017 1500 crew cab silverado. i need to wire the third brake light and the inside cap light. Please advise thank you

Les D.

11/3/2021

@NeilS We are not familiar with this process as we do not sell pickup toppers. Seems like the easiest way would be to splice into the brake light circuit either at one of the rear lights themselves, or at the wiring to the tow lighting wiring near the rear of the truck.

Neil S.

11/4/2021

@LesD I must not understand, you sell logic boxes, diodes, signal blocks, wiring and you have no parts recommendations at all?

Les D.

11/5/2021

Ok, sure, for wire you can use # DW02359-1 and # SWC502905-1 splices. You do not need all of that other stuff.

See All (4) Replies to Neil S. ∨

Brett

8/4/2025

I have the same situation with a third brake light in my camper shell. The question I have is on the input side of the converter, can you only use the left (yellow wire) and the white (ground wire) and cap the green wire and then on the output cap the green and yellow and just use the red? My concern is the limited wire that comes with the converter and second it would make it much easier to mount the converter in the brake light area with the connections and simply run a short red wire on the output up to the existing brake light wire in the camper shell.

Jameson C.

8/4/2025

@Brett You have to use both the left and right hand side circuits as that's only way the converter will know you are actually applying the brake and not a turn signal.

Brett

8/5/2025

@JamesonC Thank you Jameson, I appreciate your help!