I have a Grant (no comment!) steering wheel & horn assembly. If you google this you will find loads of people cursing these. Not only are they extremely difficult to get working they can also be dangerous!
I realised I had some sort of problem when I hooked up the battery and could hear clicking which I believe were the flasher units under the dash. Even though the horn wasn’t hooked up, the two spring connectors (you can see these in the right hand picture above) were shorting against the steering column cup. I tried to adjust this by pushing the column futher through the firewall, which seemed to work. But as soon as I put the steering wheel on the horn would sound if I turned the wheel to the left!
I’ve ordered a new horn assembly off of ebay (same make) just to see if I can get this to work. If not, I’ll have to fork out a load more cash on a decent wheel & horn assembly. To get it to the point where I could at least use the steering wheel I used electrical tape and taped up both connectors.
Update: The new adapter plate arrived but I had the same issues with clearance and the horn sounding when moving the wheel. After more research I found that a lot of people have used a GT Performance 3 bolt hub kit to resolve these issues, so I have one on order.
The new GT Performance hub arrived and right away I can see the advantages over the original Grant type. There is an outter piece that allowed me to alter the distance between the touch plate and the turn signal posts. I had hoped that my original horn button would work but soon discovered that I needed a new one so I ordered a GT Performance one.
Once it arrived it didn’t take long to fit it and after a few minor tweaks the horn is now working well. This is the first time the horn has worked since I have owned the car.
Update: Well, it works but I had the same issue with the horn sounding/shorting when turning the wheel. On investigation I can see that the top plunger is shorting against the sheath of the sterring column.
I decided to use my drill (I couldn’t find my dremmel) to remove about 5mm of the sheath (first picture below), which did the trick.
My Mustang Journey 