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I've got one last device to troubleshoot, and I'm a bit confused. I understand how the horn works in theory, but I'm unsure of how to connect it properly.

I've got an original Mk.1 Lucas indicator switch dated January 1966, and it's got 5 colored wires coming from it, which all match the factory wiring diagram.....so far, so good. But, my Autosparks loom also includes a 6th wire (ground) in the branch for the steering column. I'm assuming at this point that the black wire relates to the horn, but the diagram doesn't appear to show it.

Also, there appears to be an original wire that comes up through the ceneter of the column, and JUST protrudes beyond the upper end of the column. This must be for the horn contact, but I'm using an aftermarket horn push that has two terminals.

So, can someone explain (in simple terms) how I make use of the black wire coming from my loom, the wire coming up through my column, and a 2-terminal horn push? Does the black wire from the loom connect to the outer shroud of the steering column? Would the wire coming through the center of the column connect to one terminal on the horn push, and the other terminal connect to the steering wheel hub to complete the circuit?

Thanks very much.

See how this goes,,,,,,,

Maybe try to think of the Horn circuit as back to front as you would normally expect a circuit to be wired, What I mean by that is, in the case of the Horn, the Live wire comes from the fuse, to the horn terminal, then from the other horn terminal to the switch, then from the other side of the switch to earth.

The wire coming up through the column (from memory) is the wire coming from the Horn to the switch, Purple / Black (from memory). This should connect to the horn switch in the centre of the steering wheel with the other end of it (within the column) to the slip ring / brush assy right at the top of the column. The Purple / black wire in the loom attaches to the brush, but I seem to recall there's a 5 way connector lower down on the column where it plugs in (with the rest of the indicator switch). The Black Wire you've mentioned - I think from memory - is for the Repeater lamp on the end of the Indicator Switch

Hope that's some help but is probably clear as mud!

I believe I followed that explanation for the most part. I understand that pushing the horn button effectively grounds (and completes) the circuit, which provides power to the horn....I think.

The part I'm fuzzy on is how the connection is made between the outer column, the inner column, the brush on the indicator switch, and the horn button.

Unfortunately, my '67 Cooper S had its horn push replaced with a large button screwed to the dash, so I can't use that for reference.

Benny wrote:I believe I followed that explanation for the most part. I understand that pushing the horn button effectively grounds (and completes) the circuit, which provides power to the horn....I think.

The part I'm fuzzy on is how the connection is made between the outer column, the inner column, the brush on the indicator switch, and the horn button.

Unfortunately, my '67 Cooper S had its horn push replaced with a large button screwed to the dash, so I can't use that for reference.

The brush/wiper on the indicator stalk is the ground path for the horn button since the steering wheel centre is probably plastic it need one terminal #1 for the wire coming out the center of the column and one to ground it to the column itself ie a short lead from terminal #2 to steering wheel nut. this will complete a path to ground

minimans wrote: The brush/wiper on the indicator stalk is the ground path for the horn button since the steering wheel centre is probably plastic it need one terminal #1 for the wire coming out the center of the column and one to ground it to the column itself ie a short lead from terminal #2 to steering wheel nut. this will complete a path to ground

Ok, that's very clear, thank you.

What about the ground wire coming from the harness? Should that be connected to the outer tube of the steering column?

Have a look at the part labelled 121.



Its essentially just a stiff piece of bent wire which sits inside the top of the steering column immediately behind the horn button, with the bent end sticking out the side, covered by the slipring (122). The brass disc on the back of the horn button is earthed through the steering wheel. When you push the button in, the bent end of the piece of wire moves out and completes the circuit, earthing the horn through the slipring.

It always seemed very arse-about to me, I guess thats why they moved the horn button to the end of the indicator lever, rather than having to mess about with an unreliable electrical pathway through all those moving parts.

Tim

Thanks Tim,

That diagram was extremely helpful. In fact, that gave me the idea to pull the assembly apart this evening, and extend the wire for my purposes. As it was before, the wire just barely reached the end of the column, which would have made it very difficult to connect to for my aftermarket horn push. I then installed the indicator switch, and confirmed continuity from the horn wire on the indicator switch, through the brush, to the wire protruding from the column....excellent.

Now I just need to figure out what to do with the black wire coming from the harness, and I'm done!

Thanks again.

Another consideration is this:

Do you have a suitable horn?

If you use a horn which has one tag, and you put a feed to this,
it will permanently run as the horn will earth directly through the chassis.

I am not too familiar with the old horns, but would suspect that one with
two terminals on it would be required. One would be a permanent feed,
and the other the earth-return via your steering column button/switch.

I had a head-scratching moment myself recently when I replaced a
MkII type switch gear with a later type. The early type, as we are
discussing here, was earth return, whilst the later type uses an earthed
horn and a switched feed.

Ian

Yep, I've got a two-terminal horn. It's the one that Moss Motors sell as a replacement for the original Lucas horn. It is the same overall shape, and mounts in the same manner, but it has a plastic body. It has a good sound to it, though.....quite loud.

The black wire from the loom is for the heater, it was included from 1964.......................