I am installing an electric brake control and cannot find the break/stop wire that comes from switch. I have checked all of the wires from it and none are the right one. There are several that are hot but when the break is pressed they are not hot. I thought it was the white wire but it not showing any power at all.

 

That's because most loads are switched to ground. You need to find a 12V source and use the switch to control it.

 

Can i go into the fuese box and use one from there.

 

Connect 12 volts to one side of your load and the other side to the switch that you're going to use such as the brake switch to pull that to ground.

 

I installed a brake controller in my wife's 98 Tahoe, and connected the hot wire to one of the Auxiliary terminals located on the firewall side of the fuse box under the hood. I pulled the 30Amp fuse shielding it, and replaced it with an Auto resetting 30Amp circuit breaker.