(T) Strange Horn Problem

My 52 plate Doblo 1.9 diesel has developed a strange horn problem.

One minute the horn will work fine, then it wont, then half an hour later it will work.
It's really weird, last week it worked all week, then it stopped working, then it started working again ten minutes later when I tried it, and so on.

It's currently working, but I need it sorted properly for the M.O.T.

Last week I changed the rotary squib thingy and the indicator/wiper stalk unit, but that never sorted it.

Could the horn relay be on it's way out ? Anyone know where it is on this model ? I haven't got a clue.

Has anyone got any suggestions? It's doing my head in

It probably a dodgy earth at the horn side, take the horn off, clean up the contacts, make sure the wire to earth is sound. Check impedance to earth.

so it's NOT dependant on the position of the steering wheel..??

Thanks for that, I'll give it a go at the weekend

I don't know to be honest. It might be, that's why I'm asking if anyone has any ideas

years ago I had a car that failed MOT on horn, then realised it was only dead with wheels
" straight ahead" ,
it had worn a dead-spot in the wheels contactor "slip-ring" ,
I turned the wheel upside down - so when on the MOT ramp it always worked perfectly..

My old mirafiori 131 had twin horns at the front, which didn't work initially due to bad earth but once I had sorted that, and tweeked the adjustment screw out a bit, they were the loudest horns ever, made me jump every time just bipping it.