brakes for a tahoe

ok, ty

What power is missing? The trailer brake? The 12V charge line? Lights and / or turn signals?
Does the brake controller you installed light up (have power to it?)

On my '04 GM I had to 1) install a fuse on the under-hood fuse block and 2) fish back through the wiring harness a few inches, find the 12V charge line w/ ring terminal, and buy a 6mm nut to put it on the fuse block stud.

If I remember correctly unless the key is in run position you wont. But under the hood fuse panel on drivers side there is a dummy fuse. Position two I think. Also you need to verify that there is actually power to the fuse. On some GM vehicles the power wire is not connected.