What would be the likely cause of the horn going off whilst the car is being driven you think it must be a short circuit But can someone advise where that might be?

What would be the likely cause of the horn going off whilst the car is being driven you think it must be a short circuit But can someone advise where that might be?
Ahhh, now there's the rub, finding the short.

The first thing you have to do is isolate the wires leading to the horn itself. You'll then have to trace the wires back to the switch which is located on the steering wheel. You'll also have a wire which travels to the power source. (battery) The circuit is simple enough; unfortunately your wires are likely to be bundled with fifty other wires.

Look for clues: 1) When the horn activates, is it a long solid blast which suggests that the wires may be pressed firmly against a ground?

2) Or is it a series of halting toots which occurs while going over a rough patch of road?

It would help if you have a multimeter set to detect low voltage. Place the negative lead on a good contact point on the engine and run the positive lead along the wires and look for a spike in voltage. If you find one then that could be the source of your problem. Isolate the area and insulate with electrical tape.

Of course, you could get lucky and find a break in the wire where is has rubbed against the car body or engine and left a burn mark.

These are some general remarks to help you get started. Take my advice, if you haven't managed to find it in the first hour, take it to your dealer. It may be worth the money to you to avoid the aggravation.