The horn is located behind the front bumper. If you remove the front bumper you will see the mounting spots for It. It is held by 2 10mm socket bolts, and there is one horn for each side.

Have you tried replacing the vss sensor (vehicle speed sensor)? It is located on the top part of the transmission. If you stand over the passenger side fender looking down into the engine bay you will see the intake, under that you will see the starter connected to the transmission. If you remove the intake arm from the intake manifold, and look straight down with a flash light you will see a sensor that is located on the transmission and held down by 2 10mm socket bolts. Remove the 2 bolts and twist the unit and pull the whole unit out the transmission, unplug the actual wire harness from the sensor and reverse instructions for reesemble. If all fails then you should look into replacing your gauge cluster. Good luck