The Stovebolt Site Forums The Shop Area The Electrical Bay Horn don't toot.

I have a '51 1/2 ton burb with the original horn. Recently the horn has become quite temperamental, sometimes it toots, sometimes it don't. The connections are all good, and I believe the horn button is good.

I fiddled with the adjustment screw on the back of the horn a bit, (not that I know what the heck it actually does) and no change. Pushing on the horn button (with the truck off) would produce no sound, but when the button was released, a faint peep or pop could be heard.

Today when I was driving along, I pushed the button and the horn tooted. At idle it would not. So now I'm thinking that this is voltage related. When the truck is off or at idle, horn will not toot. When I'm running down the road with a good 7.2 volts or so from the genny, horn will toot.

Or could this somehow be vibration related?

Any of you fellas know what the problem might be here? is it possible to R&R the horn?

Thanks,

Kurt

Kurt, you can take it off but before I did I'd make sure its the horn. Put a hot wire to it and see if it "toots". It sounds like something besides the horn.
I might add I took mine off...not working at all, and I could only get it to "growl" at me. If you do take it apart and try to adjust it be aware you move the adjustment screw VERY slow and just a tat at a time. Seems these old horns can be cantankerous.

Kurt, I would remove the horn and connect a test light, or better yet a voltmeter, and push the horn and see what's going on. Alvin is right about horns being finicky.

That's my next step for sure. I have a new wiring harness in the truck, so either the horn contact at the wheel is dirty, or the horn itself is .... tired.

It seems to be working a little better with all the exercising I have been giving it as I tool around. Gettin' some strange looks from the public, however. Still won't blow when idling.

Kurt

Mine stopped also. Where did you get the wire harness?

I guess "new" is a relative term in this case. I got it about 10 years ago, and I don't remember where.....I do recall that it was around $125 and other than having a turn signal circuit, was laid out like the original. Modern wire - not cloth insulated.

Kurt

Kurt,

That faint sound you hear when you release the button is indication that the contact points inside the horn need to be cleaned and adjusted.

When you remove the round cap you'll see something that looks like this....

CLICK

Those two nuts adjust slightly up and down and adjust how the horn sounds. You want to adjust them very slowly, 1/16 of a turn makes a big difference. Up or down too much in either direction will result in no sound. There is an electrical contact point that who's gap is set by playing with these adjustments. There must be a slight gap when set right, but not touching.

I find in the two old horns I've rebuilt a light layer of rust built up on these points, and using emery paper I lightly cleaned it up.

Good luck,
Mark

Mark,

Thanks for this good info. Does the round cap just pop off after you remove the center screw?

Kurt

Yes sir. Might take a little prying - the screw is the only thing holding it on.

Mark,

I popped the horn cover off and cleaned the contacts with a dollar bill. She toots right pretty now. I always thought the screw that holds the cover on was an adjustment screw, but as you say, it's the double nut under the cover that does the tuning.

Kurt

You see - only in the USA! We can't clean with anything with dollar coins!

I guess they don't have sandpaper in NC?

Well, we do have sandpaper in NC, but something like a dollar bill or a points file works better for cleaning points. The sandpaper/emery cloth can leave little bits embedded in the points which will cause them to eventually fail-permanently.

I have used the dollar bill trick numerous times to freshen up a set of points in an engine that won't spark after sitting for a long time. Try that first. Then a file. Then new points.

Works on voltage regulator contacts too.

Kurt

On my 56 a couple years ago the horn just went off for no reason in the street where the truck was parked. I was trying to get to the battery cable after about 3-4 mins. of constant horn tone and the relay clicked and that was it. Not sure if the relay got stuck or what but it died.
It's been on my to do list to get another relay and go from there. A friend of mine has a 58 and he gave me his since he's not going to be using it.
It has 4 leads. 2 big leads and 2 small. Just curious if anyone knows which is the load and which is the control side of the relay so I can test it out before installing it.