e36 Horn works only on right spoke (not on left, not on central)

[Flyingdutchman]

Hello everyone.

I have a horn problem on my '93 E36 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!

[Greydog]

Afternoon Andrea

My bet would be the Slip Spring behind the steering wheel is at fault. A diagnostic would confirm if you have access to BMW 1.4.0 or similar (not expensive to buy and worth its weight)

Take a look at www.realoem.com put the last 7 digits of your Vin into the search box it will bring up your model. Then look at the Steering section, the small exploded drawing will give clues to what fits where plus there will be part numbers that ensure you get the correct part for your model if replacing it is required. Also if you double click the part number it should give a list of any alternatives available

Good luck with the fix

Dave

[Flyingdutchman]

Hello Dave,

thanks for the reply.

Sorry my questioning. new to these problems.

Is the slip ring the #3 in the pic?

Looking at the pic and the steering wheel itself, it seems to be just a metal bush for connecting the steering wheel metal base to the sliding pin in the column, nothing really special. At least it seems to me....may be I'm wrong.

Not understand which fault could be if everything is OK with the right "button" and the left/bottom "button" works if connected to the metal of the S/W (immediately close to the copper areas).🤔

Unfortunately (or maybe not?🤣) the model year is very basic and no diagnosis is available.

 

Thanks again for your help, bye!

 

Andrea

 

[Greydog]

From your problem it would seem to be a "wear and tear" issue ie, a lot of years of turning the wheel.

The slip ring gets a lot of wear so check it carefully 

Good Luck

Dave

[Flyingdutchman]

Hello,

I see:

- on the steering wheel cover, continuity between all pins and the contact point (where faston to be connected from slip ring);

- on the steering wheel base, continuity between right copper plated area to S/W metal and to ground; no continuity between left/lower copper plated area to S/W metal and to ground;

- continuity of the steering wheel metal base to ground, I think it is the ground via the steering column and its bolts to chassis

I think the left/lower copper plated areas lost connection to S/W metal (and ground) then the circuit cannot be closed (12V via slip ring to cover and then back to S/W metal base and ground).

Opinion? hints?

I was thinking to put a little copper plate with little soldering point to restore connection to metal/ground.

What do you think?

 

Bye!

[Greydog]

Always worth trying also worth trying, as the alternative is finding another part?

You could try cleaning all contact areas and reassembling using electrical contact paste 

Good Luck

Dave

[Flyingdutchman]

Hello Dave,

I though to buy a used steering wheel but they are usually in quite bad shape, especially the leather. Mine is mint.

And BMW made me change my mind with a new one....

I already cleaned and greased but, unfortunately, no result.

I was thinking to restore the connection with the metal base by adding/soldering copper little strips over the old or just remove the old copper plated points (and see what is below🤔) and add (soldering) new ones. At the end of the story, they are not working anyhow......I cannot do big damage🤣🤣🤣🤣

 

Keep posted, thanks for helping

 

Andrea