First thing we need to do, is establish if there is power to the horns. Four hex head screws on top of the grille can be removed, then easily undo the four tabs at the bottom of the grille, out comes the grille. The two horns are now exposed. Check connections. If connections are fine, making good contact, we need to know if there is power to them. At this point, unless Dad has a test light, or test meter...we are done. If he does test for power. This is the easy end to check for power, and I will assume, this usually gets me in trouble, assume you did check the fuse box for power as well. Just cause fuses are good doesn't mean there is power to them. Again a test light or test meter is needed. Touch the probe to one side or the other of the fuse, as you would have done with wire connections at the horn. How are you doing so far?.....