Horn Relay

[Jim Shepard]

I've recently come by a horn relay that I want to put on my B2B. It didn't have one originally but when I converted the truck back to 6V the horn didn't work (it did when the truck was 12V). It was suggested on this site that a horn relay might solve the problem. My question is: how does it hook up? It has 3 terminals marked 'B' 'H' and 'S'

I haven't been able to locate a wiring diagram showing a truck with a horn relay, although I've read that all trucks with dual horns had them. As I said, my truck is a half-ton (single horn) and didn't come with a horn relay.

[grey beard]

JIm,

Pilothouse trucks only used relays originally when the two-horn option was selected. My own truck has the dual horns and a relay in between the two, all on a factory bracket.

Your stock horn is a very simple circuit, and does not need a relay. A green wire goes from the BAT terminal of your voltage regulator up to the horn. This wire is hot at all times. The second horn terminal goes to the horn button on the steering column, where it is grounded when pushed.

If your honr does not work, first check with a test light at the norn, itself, to see if the wire from the regulator is hot. If there is current there, use a jumper wire and ground the second terminal,. The horn should sound. If it works with the jumper wire, your problem is in the circuit to the horn button. You may have a problem at the button itself, or in the wire that comes up through the steerintg box and column. Should be easy to find. LOL

[norrism1]

I had to re-caibrate my horn when I went to 12 volts. Adjustment screw under the bulbus end.

[greg g]

And is wired as shown.

If you have a three wire it is probably self grounded and the leads are bat, horn, switch.

So you would probably need to use one of those funky aftermarket plastic horn buttons and wire it hot to the switch terminal of the relay.

[Jim Shepard]

I should have mentioned that the truck is now a negative ground with an alternator. Don't know if that makes any difference. What is really perplexing to me is the fact that the horn was nice and loud when it was 12V and is now just a whimper...

[Rich Gengo]

Is it a 6 volt horn? Or did you burn up the horn putting 12 volts to it? If it's a 12 volt horn putting 6 volts to it aint going to cut it

[Jim Shepard]

Is it a 6 volt horn? Or did you burn up the horn putting 12 volts to it? If it's a 12 volt horn putting 6 volts to it aint going to cut it

It's the original 6V horn and it worked fine when the truck was 12V. There was no resister as far as I know and I rewired it with a new harness during the restoration. I suppose the horn could have been damaged but why would it have worked at 12V and not at 6V?

[Rich Gengo]

You were putting twice the power to it. I remember when I had my 53 (about 30 yrs ago) I put a v8 in it and 12 volts and changed all the lights but not the horn and that horn sure was loud but it did finally burn up. Don't know what is in a horn that makes them work but if I had to guess it didn't like all the extra voltage. It's just like your starter. Put 12v to it and it'll spin like hell---for a while!