My horn stopped working but i think it may be the new realy i installed. On the two terminals (one goes directly to the horns and the other wire comes from the harness) should one of them be hot? I get zero voltage on both terminals (im not counting the buzzer terminal which works just fine).

Red wire should be hot

There are two black wires and one red wire to operate the horns. The red wire should be hot all the time. One black wire is from the horn button on your steering wheel and provides the ground for the relay, then you should have 12v on the black wire to the horns.