Troubleshooting Lights Not Working on Auto

Updated 02/24/2026 | Published 02/20/2026

Question:

Boat trailer lights only work when lights are forced on taking off auto/forcing running lights or at night on auto and no brake or turn signal at any time. I checked the trailer ground and everything seems fine, no rust and clean contact saw sparks when tapping it to trailer. 2012 Chevrolet Silverado.

asked by: Tommy

Expert Reply:

Hi Tommy; so the lights are working when you actually turn the vehicle lights on, but not when the lights are on auto during the day? Just the running lights though? No brake or turn signal no matter what you do? Have you tried checking your vehicle connector for corrosion/damage? I would start there, then use a circuit tester like # PTW2993 to check for power. You could also hook up to a different vehicle to rule out the trailer.

expert reply by: Robin H