The Stovebolt Site Forums The Shop Area The Electrical Bay New Horn Relay Question 123 vs BSH

Preface this with my usual disclaimer of any electrical expertise. I am learning but it still confuses me.

My new horn relay (I never had an old one or the old harness) and new harness are ready to be connected together. The direction for the harness indicate connection to BATT, SWITCH and HORN on the relay. Of course the relay is not marked as such and instead has 123 for markings.

When I look at the wiring diagram I see the power (BATT) goes to the center and that appears to be connected via the coiling of the center terminal to the Switch (S)terminal of the relay. The last terminal is marked Horn (H) and appears to open in the diagram.

If I have that right. How can determine which of the terminals on the new relay match up. With the new relay in hand and not connected to anything should my little ohm meter show continuity between the BATT terminal and SWITCH terminal and nothing on the HORN terminal? I get continuity between 2 and 3 and nothing on 1. Thanks Ralph

Power comes from the battery and goes through the relay to the horn button, but there is no ground and therefor no circuit. When you press the horn button, you complete the circuit to ground and the relay closes by making an electro magnet. Power from the battery then also goes trough the relay switch to the horn. The horn is grounded and you have made a circuit and the horn blows.

Ralph,

I think you have it figured out perfectly. BATT and SWITCH have continuity while HORN does not. BATT will be the center terminal.

I wonder why they don't mark these relays better?

Stuart