Got home 11PM And went straight out to the shop. I knew I couldn’t sleep well until I had the answer.
You are correct, my battery is weak and only shows 10V across the posts.
My digital multimeter shows I have a 1 mA current draw from something, but I haven’t figured that out yet.
The horn is reconnected but does not sound when I hook the battery cable up again. The horn relay is only six months old. I disconnected the horn and just tested the horn relay by supplying a ground to the correct prong. There is an audible click and the meter shows voltage to the wire that goes to the horn immediately jumps to 10V (which is what my weak battery is showing right now).
