Why won't my horn turn off?

[tedlogan]

Hi my moggies horn wont turn off, can any one help? I've had to disconnect within the engine, but its mot time and need to get it fixed. Am I correct in thing that a horn is kind of wired like a loop that has a break in it and that when you press the horn you complete the circuit and out comes the sound? If so i'm thinking maybe the button is stuck! Or could a loose wire cause this? Any ides welcome thanks

[mike.perry]

You are correct in your description of the circuit, the feed to the horn is always live, therefore any short circuit between the horn and horn push will activate the horn. Check that the horn push spring is functioning and then check all the wiring between the horn and horn push. Disconnct the horn and connect the wires to a test light, it makes less noise

[simmitc]

A very common problem is the indicator switch and/or steering column have been moved. 1) park the car with the wheels straight ahead; 2) disconnect the battery; 3) remove the steering wheel; 4) remove the cover over the indicator switch. Now, look at the indicator switch. There should be a copper spring holding a pad onto a copper slip ring around the column. There's a good chance that the pad is pressing somewhere other than on the correct ring, and thus completing the horn circuit to earth. You need to adjust the outer column and/or switch assembly and/or the copper spring to ensure that (a) the pad is pressing on the ring, (b) the self-cancelling trips on the switch are lined up with the knob on the column. and (c) the knob on the column is dead centre between the two trips - that's why you need the car parked straight ahead. Connect the battery for testing purposes, and when all is OK, disconnect the battery, replace the cover and wheel, and reconnect the battery again.

The horn is supplied with power and the earth return is completed by the horn push. This is fed by a wire in the centre of the column, linked to the ring. If you do not disconnect the battery when removing the steering wheel, then it is normal for the tools and/or retaining nut to complete the circuit and sound the horn.

[Jamiet]

Hi Simmitc
Thank you for posting such a clear and easy to follow remedy to an issue that bothered me and my neighbours yesterday.
It is really helpful when clear step by step remedies like this are posted. Posts such as yours are gems on this forum. Non judgemental, helpful and easy to follow. Thank you.
By the way the reason mine was faulty was due to changing heater hoses. I had to remove the glove box and this In turn meant the the steering column had to be fractionally lowered. It was then that the indicator assembly moved creating the short just as you describe.