I have a Series II with the original horn (and the original wiring!) The horn doesn't work. I've been through the circuit and as far as I can tell it should. Here's what I've done
Battery fine
12 volts at one side of the fuse (the top one terminals A one and A two)
12 volts at the other side of the fuse
tested the fuse with a resistance meter, fine
12 volts at both terminals on the horn
12 volts at the spring clip under the dash
12 volts at the horn push
horn push earthing correctly
removed th horn and temporarily wired it the to battery, lots of noise
What the hell? Surely the horn should work
It's all that's needs doing for the first MOT test in 20 years. Surely there is a logical explanation somewhere
Test the horn by disconnecting both wires at the nearest bullit connectors and run substantial feed wires from the battery teminals to the horn wires. Alternatively you can remove the horn and connect the wires to a battery charger. The horn consumes a heavy current so the wiring needs to be in good condition.
If the horn does not work then there is an adjuster screw in the middle of the horn. Try adjusting it one way or the other
If the horn works OK then check the contact on the brass ring below the steering column bracket.
Check the screw holding the horn push to the steering wheel boss is tight
Also check the wire inside the horn push is tightly held by the small nut
Thanks mike.perry that pointed me in the right direction. It turned out to be a broken connection for one of the terminals in the horn, worked some times and not others...wiggling the wire around tracked it down. It's a shame the horn has rather had it so I've bought a new one, horrible plastic thing not the great substantial piece of steel, brass and rubber from the original.
Keep a lookout at auto jumbles etc and you should be able to pick up a good original type Lucas Altette horn. Just check that it is 12V not 6V. Or you may get a pair of Lucas Windtone horns. Try "Taff the Horns"
