factory GM trailer light wiring...

[FordeatinZ71]

I found today I have a problem with my factory 7-pin trailer light setup on my 04 Sierra...the only thing that works is the running lights, the brake lights and turn signals are inop. I checked the underhood fuses that were clearly marked for trailer, only found two, and they were fine. Also checked the two maxi fuses I found (one was a dummy fuse from factory, shouldn't affect my setup...but I swapped in a good one anyhow) and they were good. I checked obvious wiring I could see and it looked fine...

The truck has a warranty so I'll probably just let the dealer fix it, but I don't wanna take off work to drop it off so I'd like to fix it myself if its something simple...any ideas guys?

[duece325]

make sure you plug the trailer into another vehicle to make sure its not the trailer. i had a similar problem with a trailer i had, turned out to be a bad ground on the trailer

[FordeatinZ71]

Actually I spliced into the actual taillight wiring and the trailer works fine. Just need to fix this factory crap. Thanks though, that's something a lot of people might not think to check!

[ToyHauler]

so its probably in the connector, sometimes the terminals are corroded, some times the wires are, not in the best place. i use spary stuff when, sorta like terminal spray to seal the wire connections in the connector before i put it together.

[FordeatinZ71]

Yea, you're probably right...its going into the shop soon...