Have you tried unplugging the horns one at a time and seeing if it works?

If one horn is faulty then neither will work.

 

hi , i will try that. just looked at handbook, and there is no fuse listed for the horn, so deffo something has failed,.

 

Check fuse F1 under the bonnet - it controls the horns , rear fog and ECM - does the rear fog work ?

Suspect not much different to the F wiring ?
http://www.mgfcar.de/schedules/sb19.jpg

 

OK... simple test - set the alarm off (Arm the alarm with you sat in the car, wait a bit - move around turn the lights on)

If horn works with alarm your fault will be the rotary connector in steering wheel, if not then its a wiring / fuse fault.

I will dig up wiring diag and post it in a bit.

Edit : ahhh Ian beat me to it with the diag

 

OK... simple test - set the alarm off (Arm the alarm with you sat in the car, wait a bit - move around turn the lights on)

If horn works with alarm your fault will be the rotary connector in steering wheel, if not then its a wiring / fuse fault.

Neat bit of troubleshooting !

 

I had this problem 2 weeks ago. Tried the alarm it sounded the horn, so the problem is the coupling between the steering wheel and the the loom.

Remove the plastic cover from the steering column, wiggle the wiring plug between the coupler and the loom. DO NOT touch the thick yellow one this is the airbag connector.

If this fails to activate it then you are down to removing the airbag and trying the connector on the steerring wheel side. That involves taking the precautions for removing the airbag. I too only had one horn so don't let that bit throw you, some models may have two, others only one.

 

If all else fails, you'll be needing one of these.
http://www.ruighaver.net/bumperstickers/stickers/horn.htm