I'm having a bit of trouble getting the horn working. I have put an additional earth on at the horn end. It was showing about 9v at the horn push but I've cleaned the grease out and now nothing. Any help appreciated.

 

Brinny
Start by checking that there is current at the horn push (using a test light). If there is, then head in the footwell, you should see a copper wiper running against a hole in the column outer that allows the wiper to contact the inner column. The other end of this wiper is just a rolled end to the copper wiper and it should have a bullet connector with a wire attached to it, in it. If all good here, then fuse and relay next, the relay is behind the LHS headlight nacelle inder a plastic cover just forward of the header tank, together with the fan and headlight relays.. There is a horn fuse in the cabin fuse box, (no. 11 in main fuse box on my car, also does washers and aircon controls) and but see next para too:
Note also (although none of the Jaguar official diagrams show it!) the front-most fuse on the LHS inner wing fuse panel which is shown as fusing the auxiliary fan, ALSO fuses the horn circuit! This omission is also omitted the attached horn circuit diagram that you may find useful too.

 

I did have about 9volts at the hornnpush but this disappeared after I sprayed electrical cleaner in. Brilliant advice as usual greg and I will have another go tomorrow. Had enough today so pulled a Guinness out the fridge!!

 

Only one?