Horn stays on if ignition is on

[Gosse]

Good evening,


I've swapped my heater core of my VW Bora 1.9 TDI building year 1999. After connecting up my battery, I tried starting my car.
Everything worked, except the fact that my horn continuously keeps going off when I turn the key to ignition. It won't stop, unless I pull the fuse, or turn off ignition.

If I try to use the horn, without the key into ignition, it won't work at all.

What could be the cause of this? Anyone with a suggestion? Would be much appreciated. Thank you

[GreenV8S]

Did the horn previously work with the ignition off?

[tapkaJohnD]

When a fault occurs after any work, review what you have done.
You have caused this fault so undo the work and find the cause.

Almost certainly you have nipped a wire in a fastener and shorted the supply to the horn.
So look for crushed wires.

JOhn

[Gosse]

GreenV8S said:

Did the horn previously work with the ignition off?

Yes it did use to work perfectly fine.

tapkaJohnD said:

When a fault occurs after any work, review what you have done.
You have caused this fault so undo the work and find the cause.

Almost certainly you have nipped a wire in a fastener and shorted the supply to the horn.
So look for crushed wires.

JOhn

Will try this, thank you.

[GreenV8S]

Did you dislodge any relays? If so, check they went back correctly. An electrical short between the output from the horn switch and a switched ignition supply would fit those symptoms - in that case I'd look for a blown fuse on the horn supply too.

[Stiggolas]

Horns usually use a switched earth rather than switched 12v, so it looks like a trapped wire from the switch to me.

Cheers

[TroubledSoul]

This happened on my S6. The steering wheel squib ring cabling had basically disintegrated inside the ring itself and shorted.