If it has two terminals, check to see if you can detect that one is not insulated. Check for markings. Maybe used before horn relays, before a one terminal/case bolt ground. Do a continuity check on each terminal to the case. Take off paint to get ground test spot.
You say it's an "original". You have a 1954 truck. So if you mean original 1954 horn, it has ONE hot terminal supplied by a horn relay and the case is the ground to chassis.
This wiring method started in 52/53 in trucks and earlier in cars (back to 1942). Some early GM vehicles with dual horns had relays.
I assume it has two terminals or you wouldn't be asking about polarity. You don't have an original 54 horn if it has two terminals.
Last edited by bartamos; 03/13/2024 8:59 PM.
