about the same time my Horn stopped functioning, i noticed the OIL PRESSURE GUAGE was almost maxed out..even when not revving up

i think it even showed pressure when the engine was off, but key was turned to on...
well.

after a test, a book said to bring the wire to the oil pressure guage and ground it to see the guage show a sign of life..(it sparked at 1st.but no movement on the needle, and no further sparks).

any ideas...
i had to re-wire the horn, and that still looks fine..
i checked engine bay fuses, and under dash/ steering wheel fuses..but the cabin fuse box is missing its cover, and display on what goes where with correct voltages..

any help please.