Troubleshooting Trailer Lights Not Working with a 2017 Chevy Silverado 3500

Updated 10/27/2025 | Published 03/11/2025

Question:

I have a 2017 Chevy 3500 connected to an aluminum horse trailer. Made a 2000 mile trip in December and all lights worked fine. Parked trailer until this past weekend. I now have no parking lights and only have turn signals/brake lights if I dont turn on the parking lights. If I disconnect the parking light wire from the trailer side the turn/brake lights will not work at all. I have tried the truck on another trailer with similar results. I had no parking lights and only had blinkers/brake with the parking lights off. I am not sure where else to be looking

asked by: Randy K

Expert Reply:

Hey Randy, thanks for reaching out!

Light issues are frustrating to deal with, but since you've already confirmed the issue exists with the same truck between multiple trailers, it's safe to say you need to be looking at your 2017 Chevy.

Usually, inconsistent lighting issues like this are related to a bad ground or bad connection somewhere. Start off by checking the 7-Way socket on your truck. Look for any pins that might be damaged or have debris/corrosion in them and clean it. You'll want to disconnect power to the 7-Way or the 7-Way directly prior to cleaning anything, but once it looks good, I recommend protecting the pins with Dielectric Grease # 11755.

Be sure your ground on the truck is also secured to a clean, bare-metal surface for the best contact.

Let me know if you're still having issues after checking all of this and I'll be happy to help you keep looking into it!

expert reply by: Jon G

Jon G.

10/27/2025

Hey Randy, did cleaning and protecting the 7-way socket with the dielectric grease clear up the lighting issue on your Chevy? Your update could make it easier for others troubleshooting the same problem.