Hi all .... been scouring the forums and can't find the answer to my question so I'm sure one of you clever people will know ...

Does the original horn ground to the chassis and the two wires that plug into it are they both +ve to activate the horn when pressed? ...... I'm guessing two wires so one from each horn switch on the steering wheel?

One side (that is, one of the connectors) is earthed to the chassis.

Usually when the horn doesn't work it's either the chassis earth (run a better one) or the lucar connectors on the horn itself (clean and smear with vaseline).