Powering 3rd Brake Light and Dome Light on Topper for 2025 Silverado 1500

Updated 01/16/2026 | Published 01/15/2026

Question:

I have a 2025 silverado and I need to wire up a 3rd brake light and dome light in my topper. I would like to have constant power for the light. Do you have a harness that does all this? Thanks

asked by: Paul U

Expert Reply:

Hey Paul! To power the 3rd brake light you will need to tap into the yellow and green wires on the towing harness and use the 3rd Brake Light Logic Module # PP20-702 to filter out the turn signals. Older Silverado's had a dedicated wire but it is no longer accessible on the 2025.

To power your dome light you can tap into the 12V auxiliary circuit on the 7-way wiring so you have dedicated power. If you don't have a switch on the light you will want to add one. I'm assuming you wanted constant power on the dome light, it wouldn't work well on the 3rd brake light unless you had multiple circuits for stop/running light functionality.

What kind of truck topper did you add?

expert reply by: Robin H