Electrical: Horn relay wiring

[tim333]

57 Commander: I took off a working horn relay to clean surface rust off the mounting tab, now it doesn't work. Right to left; black 12v wire, blue wire and 2 black horn wires? Schematic shows black 12v wire in the center and I hear horn click when I put that wire in the center. Horns work if I put 12v wire directly to the 2 black horn wires.

[Skip Lackie]

Most have markings near the contacts. B usually means battery, S means switch, and the last one will be marked H for horn or something else.

[tim333]

That was it Skip, thanks. Upside down from the pic in the schematic.

[Royzon]

Qu: I bought a new horn relay and didn’t hv luxury of having old one; so not sure how to wire it; on relay, the 3 prongs are marked 1,3,5... no letters.

[Royzon]

Skip, what if the relay is marked 1, 3, and 5? Thx

[gordr]

Well, you could meter it out. Assuming you do have an actual horn relay, and not a general purpose relay. Using an ohmmeter on low ohms scale, one terminal should show open circuit to either of the other two. That one goes to the horn. Of the remaining two, one is common to the relay moving contact and to the "hot" end of the relay coil, and the other is the "cold" or button end of the relay coil. So hook the horn up to the terminal identified as "horn", and connect the other two to battery and to the button, respectively. Try it. If the horn sounds, and goes off when you release the button you got it right. If you get one click upon pushing the button, and nothing else, then you got the other two reversed. It won't hurt anything, but do disconnect if you had the wrong connection initially. Connected wrong, the relay will "latch", because with the contacts closed, the coil "sees" ground through the horn. Leaving it latched for a long period of time might burn out the relay coil, and could run down the battery if left overnight.

[ddub]

Skip, what if the relay is marked 1, 3, and 5? Thx

Would these refer to the European universal number system for auto electrics? I have read about that but have no knowledge. Someone else here must.

[Skip Lackie]

Would these refer to the European universal number system for auto electrics? I have read about that but have no knowledge. Someone else here must.

I believe so. One should be able to Google Marchal or Cibie horn relay wiring and their sites should label the various contacts. That said, Gord provided a way to determine which is what.

BTW, this is a three-year old thread. Glad some of us are still around to respond . . . . .