Horn wiring - 1953 Series II

[BRG?Mikey]

I wonder if there is anybody that can help with the above. I've spent a fair amount of time looking for relevant old threads on the chat (and online) but I don't seem to be able find an answer to my specific query as most/all of the information I've found seems to relate to the later Minors with an indicator stalk. My workshop manual has a wiring diagram of course but that is a schematic, rather than a picture, and doesn't give the answer to my query. I'm no expert at interpreting wiring diagrams though.

If I press the horn push at centre of the steering wheel, there is a click at the horn itself. For clarity, the horn does work and the wiring from the horn to where the steering column is mounted to the underside of the dash is fine - if I 'short' the wiring from the purple wires at that point (which lead to the horn) to earth (via the ring around the steering column where the sprung/tensioned 'strap' is - not sure of the correct term), the horn works fine. By fiddling about with the wire that runs down the centre of the steering column from the horn push, I have occasionally been able to make the horn push work correctly. When all I get is the click at the horn, the horn push wire shows less than a volt on a multimeter. I am therefore pretty confident that the fault lies with the 70 year old wire that runs down the centre of the steering column, probably at the point at which it exits the steering column (the connection from the wire to the horn push itself is fine). The problem is that I can't find the other end of that wire (that is, where the wire exits the steering column) and therefore can't get access to that end of it.

I could get some sort of endoscope with a feed to a mobile phone and push it down the open end of the steering column (where the nut that holds the steering wheel on is) to see if that gives me the answer but I'm hoping that the community can give me a definitive answer without having to incur that cost - it might not give me the answer anyway. A picture from you would be very helpful, though I know access to that area requires some spinal flexibility! To be fair, my car isn't very original and seems to have wiring from more than one wiring harness, and this may make diagnosis difficult. Many thanks.

[Classiccars]

Cheap Endoscopes available online.They have a light o the end and a screen at the other.Work well.

[geoberni]

I believe you'll find it very similar to the version used on the 1000 models with a central horn push. So you might find this parts manual illustration helpful.
I've never had to removed my steering wheel, so I don't have any photos....

Horn.JPG (58.16 KiB) Viewed 1113 times

[BRG?Mikey]

Thanks to both. It looks as if I'll have to try the endoscope as the diagram provided doesn't seem to relate to what I can see on my car - could be my untutored eye though. I hope I don't have to take the steering wheel off - seems like a 'sledgehammer to crack a walnut', having read various threads on the chat on that subject.

[StillGotMy1stCar]

Just I thought, but as I understand it the earth return is via the steering rack, ie; there is no earth brush on the steering column, just the one that goes to the slip ring, item 14 above. It might be worth making a temporary earth on the steering column with a jump lead before investigating the short wire connections at each end in the column and finally the horn push.
I am sure I read somewhere of someone making their own arrangement for the column earth because the steering rack was no longer providing a reliable earth.
Take extra care if you do decide to take the slip ring assembly apart as I believe the plastic insulators between the column and slip ring and are on longer available, items 15,18.

Regards John.

[BRG?Mikey]

Thank you John. I've had a word with Bryan Gostling (MMOC Series II spares guy - very helpful) and he seems to confirm what you've said. It seems that re-wiring the short length of wire from the horn push down might be a real pain (the bottom end of it not accessible - may have to remove steering wheel, and/or possibly the whole column!) so I might have to see if I can cobble together some sort of alternative earth as you suggest. I can't say that I can think of any easy way of doing it though, at least without it looking like a real mess. Ridiculous for a length of wire that can't be more than a foot long! I will try the MMOC Series II register and see if they have any bright ideas. Thanks again. Mike

[mike1864]

Are you sure the push button itself is providing a dead short when pressed?
And its peripheral contact to the column's hub is good?

[myoldjalopy]

Are you sure the push button itself is providing a dead short when pressed?
And its peripheral contact to the column's hub is good?

Yes, I would be checking those. In any case its not difficult to remove the steering wheel - assuming you have the correct socket (I believe it is 3/4 whitworth, although other sockets may fit). Make sure you disconnect the battery beforehand to avoid accidentally sounding the horn in the process. Once you have loosened the nut, leave it on while you loosen the wheel by trying to wiggle it off, otherwise it may come off suddenly and whack you in the face!

[svenedin]

Yes 3/4 WW box spanner which is 1”5/16 or 33mm.

[geoberni]

Yes 3/4 WW box spanner which is 1”5/16 or 33mm.

Typical, ....the biggest I currently have is 32mm, which fits my Kuga Mk1 Oil Filter top.

[mike1864]

Hang on a minute.
I thought the column slip-ring is the mechanism that carries the switched earth from the pressed horn button towards the horn.
So it shouldn't be permanently giving you an earth.
If it is, surely it would be permanently sounding the horn via that purple wire.
Very confusing. I'm wondering if the whole thing has been re-wired in a non-standard way.
Has this all worked before, or is this a new (to you) car?
Is the other terminal on the horn itself wired to the battery feed, or to chassis?
Forget about removing the steering wheel till this aspect is sorted.

[StillGotMy1stCar]

Yes it is a switched earth circuit, this is why I mentioned earlier about checking the actual steering column is providing a good earth before investigating further as the earth return is through the steering rack, the top bearing is made of felt so insulated and there is no other brush on the column apart from the one on the slip ring. If the actual column isn’t providing a good earth it may be possible to raid your “box of bits that might come in handy one day” and make something to do the job, an old motor might have a suitable brush holder and carbon brush.
Another option would be to use a relay to reduce the current through the switched circuit to around half an amp or less, I expect the horn draws about 4 amps.

Regards John

[mike1864]

The top bearing on my Series 2 column is rubber. So I too have always assumed that the column's earthiness comes only via the steering rack; lots of metal and well lubricated cogs and drives.
I just measured the resistance between the horn switch retaining screw in the side of the hub and a random fixing bolt under the dash; 0.1 ohm. Good to handle 120 Amps!
The OP needs to report back on his own multimeter's ohm measurement between these points.
And on the resistance between the top of wire in the column and the slip ring it's supposed to connect to.
But I remain puzzled that his slip ring constitutes a good earth without permanently sounding the horn when the horn wire is connected to it.

[BRG?Mikey]

Thanks all. I've got myself an endoscope so I'll be doing a bit more investigation over the next few days. Good of you to provide so much info - I'll have it with me while I'm upside down under the steering column......

[mike1864]

I still think the resistance measurements I suggested on Jan 27th will tell us more than an endoscope would.

[momo67]

heyy
endosocope... they're up for grab online.. cheap and trusted indeed!!!

[BRG?Mikey]

Hello all. I used the endoscope and that did at least help me to understand where the wire actually went. There were no apparent breaks in it as it went down the steering column and it seemed well attached (solder) to the copper ring. In the end, the wire was compromised near the horn push itself. It looked OK to a casual view but on closer inspection it was only attached to the terminal by a few wire strands (hidden under some sort of sticky black insulation). In the end, I replaced the end (ring type) terminal, trimmed a bit of the braided insulation, snipped of the end of the wire, and re-attached via a new ring terminal. Result - a working horn! I'm sure I've made this more complicated than it needed to be but thanks very much for your help.and advice.

[mike1864]

Good result. Contact via a single strand (possibly intermittent when hit with a high current) would account for the "click" symptom.
I'm still puzzled that the slip ring was reported as providing a permanent path to earth. I suspect the OP was actually touching the horn wire to the column, not the slip ring.
You did remember to put the Woodruff key back? You'd find out at the first corner!
PS I was talking rubbish about aligning the spokes; that only applies with the later, splined, steering wheel mounting.