I just picked up a new to me 86 Formula on a nice Phoenix trailer. I Uhauled home with a five pin into a round connector. Not sure what that is called. It all worked great, side lights, running lights and brake lights. When I plugged in to the connecter on my Chevy Suburban, only the brake lights worked. Any ideas why that might be? Thanks

could be the harness on the suberban might have a bad plug or ground. do u have a nouther trailor u could hook up to besides the new boat one?

my silverado and sierra both blow fuses all the time and only some lights work . check the inside panel and the panel under the hood .

on later model GM's the trailer lights are fused seperatly...great idea so does not kill all the lights..

All late model trucks regardless of brand are built like this. Although I hesitate to call them late model. GM started building their trucks like this in 1999.

shekmark.......It's likely a fuse. Trailer lights have circuits if their own and have nothing to do with your tail lights. Your owner's manual will tell you which fuse to check.

Use a test light or trailer plug tester to determine if you have signal at the plug on the back of your truck. If you don't, it's a fuse. If you do, it's a trailer issue.

Buck

Clean the connector on the Suburban....I get the same symptoms from slight corrosion on the connector, every year up here in rain country.