Horn works only on right spoke (not on left, not on central)

[@Flyingdutchman]

Hello everyone.
I have a horn problem on my '93 325i convertible Euro Spec.
I have the 3-spoke sport steering wheel, without airbag. You can see it in the picture (even if disassembled and just placed in position).
I realized that the horn only works if I press on the right spoke, it doesn't work if I press on the left one or on the bottom central spoke.
Since it works on the right spoke, its entire electrical system is OK (horn, fuse, relay, sliding contacts, wiring, ground....).
There must be a problem with the steering wheel contacts.
I dismantled the steering wheel as you can see in the pics, in the 3 push areas on the steering wheel there are 3 contacts on the cover which, when pressed, come into contact with the copper-plated areas of the steering wheel base (you can clearly see the imprints of the contacts themselves) causing the electrical contact to close and the horn honking.
Cleaned the contacts, cleaned the copper areas, put some grease for electrical contacts, nothing happened. Everything just as before.
I did a test with a copper cable: I connected a contact point on the cover iwith its copper-plated area on the steering wheel base. Nothing is happening.
Instead it happens (not always, I have to move a bit with the test cable) that the horn sounds if I touch the area of the steering wheel base immediately close to the copper-plated area.
In short, it almost seems that the copper-plated area that should favor the contact and closing the circuit is isolated from the base of the steering wheel.
And this is the same for the left racespoke as for the low central spoke.
I don't know what exactly the problem could be and therefore how to solve it.
Do you have ideas? has this happened to anyone?


Thanks for your help
Greetings

[@Flyingdutchman]

HI.
This morning I did 2 tests.


The first.
I repeated what I did yesterday:
- I connected the wiring faston to the steering wheel cover
- I took a flying electric cable, for testing
- I connected each pin of the cover with its copper-plated area on the steering wheel (with the test cable)
The right "button" pin, if connected to its copper-plated area, makes the horn sound.
The pins of the left and bottom "buttons" do not sound the horn if connected to the respective copper areas.
The pins of the left and bottom "buttons" when connected to the copper area of the right "button" cause the horn to sound.
The pins of the left and bottom "buttons" make the horn sound if connected to a metal point on the steering wheel immediately near the respective copper areas.


The second.
- I detached the faston from the steering wheel cover.
- I put the faston in direct contact with the copper-plated areas
The faston in contact with the copper-plated area on the right causes the horn to sound.
The faston in contact with the copper area on the left or at the bottom does not cause the horn to sound.
The faston in contact with a metal point of the steering wheel immediately near the left or lower copper areas causes the horn to sound.


It seems that these blessed copper areas, which should facilitate the closure of the contact and the electrical circuit, are isolated from the metal base of the steering wheel.


I don't understand how this could have happened and above all I can't think of how to fix it.


Ideas?


Thank you!

[JDStrickland]

I think the trouble you are having is behind the steering wheel.

[samy01]

Honking is very important in italy. Also they do inspections in europe and the horns must work.

Maybe hidden corrosion isolated the parts. Don't know how likely that is.

I'd measure resistance from the left copper area to the metal around it. It should read infinite if there's no connection. Maybe push around on it with a screwdriver to see if you can get a connection to show up. Then the same on the right. Should give a low number because it's good.

Only ways to solve I can think of:

1. Ignore
2. Create an alternative connection between copper and steering wheel metal without impairing safety.
3. See if you can remove and replace these copper parts and insert new ones. See what's going on between copper and metal of the wheel.
4. Replace steering wheel

[@Flyingdutchman]

I think the trouble you are having is behind the steering wheel.

Hello, thanks for replying.
Do you mean the slip ring #3 in catalogue page?
I have a very basic steering wheel, it has no airbag, no buttons, only the horn. It is very very old style.
Looking at it (see pics) and the catalogue drw, it looks like a metal bush only. just to connect (and bring) 12V from the white little sliding contact on the steering column to the faston to be connected to the steering wheel cover.
It is far far away to look like a "modern" E36 slip ring (picture from web).
Then, not able to understand how it can fail if all the system works pushing the wheel on the right but not if I push on the left
Can you explain better?
Thanks a lot!

[@Flyingdutchman]

Honking is very important in italy. Also they do inspections in europe and the horns must work.

Maybe hidden corrosion isolated the parts. Don't know how likely that is.

I'd measure resistance from the left copper area to the metal around it. It should read infinite if there's no connection. Maybe push around on it with a screwdriver to see if you can get a connection to show up. Then the same on the right. Should give a low number because it's good.

Only ways to solve I can think of:

1. Ignore
2. Create an alternative connection between copper and steering wheel metal without impairing safety.
3. See if you can remove and replace these copper parts and insert new ones. See what's going on between copper and metal of the wheel.
4. Replace steering wheel

Yes, indeed, honking is a communication way
I'll do tests, as well.
Option 1: I cannot
Option 2: the fix I was thinking about, I'm no able o se any other fail cause.
Option 3: this I could do, as well. probably the best. Little copper part, soldering and ok (I hope)
Option 4: I thought but BMW made me change my mind ( >700 €)

I'll post results
Thanks