All, I recently posted that my horn has suddenly decided to stop working - just when I needed it. I got out there today with the multimeter and this is what I have discovered - all with ignition on: 1. I have 12 volts going to the horn. 2. When the horn button is pushed and I have my multimeter across the terminals I get no volts. 3. When I earth the horn to a known good earth I get no sound. I am suspecting either: The switch in the steering column or the horn itself. Before I start to take the wheel apart I'd appreciate anyones views. I am perplexed as to why I get no sound when I short the horn unless its kaput. I should also point out I have an MCJ steering wheel - in case that makes any difference. All was working until a few weeks ago.
I wouldn't have thought you would get any sound when you earth the horn, but I expect you wold if you took it off, and connected it across the pos and neg of your battery. If you have 0v at the horn when you push the button on the wheel, the switch is knackered, or the cabling from the switch to the horn is knackered. You could test the button or switch by using your multimeter on continuity and pressing the button with the probes on the terminals. You would need to disconnect the wiring from the button though so there is nothing connected to it. If you have continuity across it when your press it down the button/switch is fine. You can also test for 12v at the button, and check continuity of the wiring from the button to the horn with the horn and button disconnected by placing our multi meter on the cable terminals at either end. If the probe leads are to short use a scrap bit of wire to extend one end by pushing it into the spade termianl
If it's a later horn: should have 12V on one terminal (at the horn) with the ignition on. Get a piece of wire and short the other terminal to ground. The horn should sound. If it doesn't, the horn is duff (or you could test it by taking it off). Set your meter to ohms. and connect it in series with the horn ground line: one terminal to horn -ve cable, the other to ground. Press the horn button. The meter should show zero ohms. If it doesn't, summut up with the switch wiring.
Snotty - its a 1974 with 12v at the horn with ignition on. When I tried shorting out the other terminal to a good ground I got no sound.
If you've got 12V on one side and a good ground on the other, sounds like your horn may be duff . Does the horn button switch the ground properly (assuming the ground is switched on earlier busses - I'm used to late lates where the ground is switched)?
In my experience if you earth the horn unit itself to the chassis you either..... A. get deafened B. bang your head as you jump with the noise! I'd guess the horns broke!
Fixed mine the other day. The brass contact ring on the underside of the steering wheel had worn right through to the plastic. Replaced and alls good again.
