My neighbor's 1988 Chevy Caprice's horn stopped working. No other circuits appear to be affected, and there's no fuse just for the horn.
I pulled the lead off the horn and applied 12V straight from the battery to the horn's terminal. The horn sounded normally.
After reattaching the horn wire I pulled the horn relay out from beside the fuse box under the left side of the dash and sent him to AutoZone to buy a new one. Nine dollars later, he was back with it. I plugged it in but still no horn when the buttons are pushed.
I then pulled the relay back out and measured each of the 3 flat connections it plugs in to:
The bottom one had a steady 12V.
One of the others has continuity to frame ground when checked with an ohm meter.
The third lead has no voltage OR a ground.
Pushing the horn buttons on the steering wheel while measuring the 3 relay contacts does not change their respective readings at all. It appears the relay is not receiving the input (ground?) from the steering wheel.
I'm thinking the problem is indeed in the steering wheel, and will cost the guy big bucks to repair. Am I missing anything here?