Head scratcher

I got a mind bender in the shop. Horn don't work. Put a jumper on the ground connection and the horn blows great. Took the switch apart, it's the one in the turn signal switch, it looks fine. Put it back together. Hooked my teast light between the ground wire and the positive lead at the horn. Pressed the button and the test light lights up bright. That tells me that the switch and wiring to the horn are working. Hook everthing back up no horn. Oh well, it's a long weekend and I shouldn't even be thinking about the dumb thing.

Go sit on the toilet a while and the answer will come. Works for me, I wonder why.

Tom, did you hook the positive lead of your test light to the positive lead of the horn while that lead was plugged into the horn? See if you can get it to light with the test light in parallel with the horn leads. Slide the tip of the lead up under the plastic cover while it's hooked to the horn.

Sounds to me like you have some resistance in the circiut. The light does not pull enough current to matter but the horn requires more and the resistance is not allowing enough to get through to blow the horn

That's where i'm going when I get back to the shop. The prob'em has to be with the switch wire,the ground. It goes straight from the switch to the horns. So I'm going to ground it at the plug under the dash to see if that will toot the horns. There are two connections. One under the dash and the other at the horns.

If I am not mistaken it is carrying 12 volts and works when it is connected to ground, so just read it and see if it has full voltage!! If it does, then the ground is bad, right??? Probably a bad switch, if you have full voltage!! Good Luck Tom!!!

Check the connections to the horns and make sure they aren't switched. BTDT. If you switch them, the horn does not work.

Leave the switch lead connected to the horn and put your voltmeter from the connector to a good ground. Push the horn switch and see what the voltage is. If it's close to 12 volts, then the positive lead is OK. Then, connect the meter to the ground that the horn uses. If the voltage is lower when you push the switch, you have a bad ground.

I got oneof my horns to work by disconnecting one of them. Neither works when both hooked up. 76 B

The horn switch ground wire is pressed in place when stalk is pressed in. Ground wire fits in a small flat area when stalk is installed. I've had 2 of these with broken wire strands. Meter and lights work OK but won't conduct enough power to work the circuit.

I did quite a lot of experiments with horns on cars for a buddies Mazda PU and on my MG. All of the responses above are on the right track..
It takes almost 1.5 amps @ 12 volts to properly sound both of the horns.
If you have high resistance connections anywhere in the circuit, you are dropping your voltage before it gets to the horn and they won't sound.

Ed

You guys wouldn't be trying to talk ole Tom into replacing his test light with a meter...would ya!!