If you find yourself with non functioning horns you should check that the horns are getting an electrical signal before you rush out and replace them. You will need a helper for this unless you have a set of long alligator clips.
Testing for signal is a simple as attaching your volt meter clips to the two electrical connections on each horn and pressing on the horn. If you see no signal try connecting the positive wire to your volt meter and the negative on your volt meter to a good ground and try the horn again. If you still get no signal it means there is no electricity getting to the horns and your horns may not need replacement. If you are getting a signal and no sound there is a good chance your horns are bad and need replacement.
Replacing the horns is a simple job. Open the hood and locate the horns. They are on the right hand side behind the grill, in front of the condenser and radiator. The horns are held in place on a bracket but you do not need to remove the bracket.
If you are only replacing one horn you can just use a Philips head screw driver, remove the wires and then use a 13mm wrench to remove the horn from its mount. If you are replacing both horns you can remove the wires and then the single 13mm nut holding the horn assembly to the bracket.
Installation is the reverse of removal
This photo illustrates the location of the horns (red arrows) in front to the condenser and radiator.
This photo illustrates the wires (yellow arrows) that you can use to make sure the horns are getting a signal, and the 13mm nuts (red arrows) securing the horns to their brackets. Note: this photo is taken from the rear with the radiator and condenser removed for clarity, you do not need to remove these to perform this job. Installation is reversal of removal.