Bob;

Shayne has it right. Fuse 2 supplies Brake lights, Reverse Lights and Horn. If the other loads work OK, it's not the fuse.

How did you verify brake light switch is working? I would check brown wire at original pressure sensing switch (and where the upgrade switch is paralleled) for IGN power, and Red wire for power when the pedal is depressed...if that's OK, then proceed to the back of vehicleand check red wire...remember, there is also a six pin connector under the dash for all the wires heading back to the trunk.

Good Hunting