Hi thank you for your question hope this helps.
12v + on the traile plug comes from the under hood fuse box. The power comes from the fuse for the marker lights, brake lights turn signal fuse.
So what are you saying you are not getting power at the trailer plug at all, ie when you step on the brake, turn on the lights?
what year is your Hummer H1?
not sure what year the hummer is as it belongs to a friend. everything on the plug is working except the 12v+ point. so I am looking for a fuse or fusible link that may be blown
he has a trailer that has a hydrualic lift on it
i think it may have blown a fuse or something, because there is no voltage at that point on the recepticle at the rear of the hummer
OK I see, You need to look in the fuse box under the hood it will say trailer. You should also look under the truck were the wiring is there may be a inline fuse, But this is year specific so look in both.