Have been pulling a trailer with my '99 Silverado without a problem. Moved the brake controller to '04 Chevy Suburban. Has power to it, comes up with 'n/c' - not connected as expected since trailer wasn't connected. Pulled trailer 7-pin plug into socket ....no trailer lights. Tester indicates as best I can see that there is no power to socket. Also, bought vehicle used but to the best of my knowledge, factory tow package and vehicle has never towed anything.
Checked fuses in engine compartment fuse box and all appear to be good. Pulled a few of the trailer fuses and with tester proved to myself that there is power at the fuse box.

I don't really see much in between the fuse box and socket by hitch except the wiring. I know in the old days (I think) they installed wiring but it wasn't hooked up but I don't see anything like that. And I even went to the dealer and he indicated that it should work out of factory.

I'm not sure what I'm missing here except my family with whom I was going camping this Labor Day weekend.

Help!

 

Shot in the dark here - is the large 40-amp fuse installed? It came attached to the trailer brake pigtail on my 01 Burb, and it is not installed by the factory. It's the circled one in the pic below:

 

so you don't have power for the electric brake control pin but all the other pins (turn, tail, brake and reverse lights) at the 7way connector work normally?

 

I know on my 97 Tahoe that the brake controller wire was tucked aside(blue wire) and had to be connected if a brake controller was installed.. I know my 07 has the power studs but I have not looked to see if the brake controller wire is there and if it needs to be hooked up....

Nut shell check around the under hood fuse panel for any unused bundled wire, could also be near the master cylinder... it may also already have a ring terminal installed....
I don't have or use the brake controller but the above info is what I have found in general exploration of under hood Easter eggs..

 

Hazard switch is notorious for going bad and causing issues. Had to replace my turn signal mechanism. fixed the problem. It drove me crazy for years!