Horn Not Working - Now What?

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Billy1972
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Sat Mar 23, 2019 10:45 pm

My horn hasn’t worked on my 1987 325i convertible since I bought it, so this is what I’ve checked and replaced so far without joy!

Fuses - ok
Relay - ok
Actual horns - Taken one off and tested it and it worked
Steering wheel horn slip ring - replaced new, still nothing?
Steering wheel round centre cap - replaced new, still nothing?

Any suggestions on what next? Driving me mad!
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Brianmoooore
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Sun Mar 24, 2019 10:30 am

"What next" is logical testing!
Does relay K2 click when someone pushes the horn button with ignition on?
What happens when you pull out K2 and link together pins 30 and 87 of its socket with a piece of wire?
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Billy1972
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Wed Mar 27, 2019 10:44 am

So as part of the logical testing I took the car to an auto electrician was has the experience and tools that I don't and here are the results.

Firstly the K2 relay is working fine, he bridged the relay with a wire and the horn worked.
He then tested the newly installed slip ring and when earthed that worked fine as did the centre steering wheel horn.

It transpires that the actual steering wheel column wasn't earthed and there was a break in the earth somewhere down it.
He went down the column resulting in a break in the earth in the engine bay at the steering column knuckle and when he bridged it the horn worked.

So what he's done is bridged the knuckle with a piece of wire making a temporary earth and now I have a working horn again.

I'll be looking at replacing the knuckle when the temporary fix breaks (if it breaks).

Has anyone else experienced this problem at the base of steering wheel column where it feeds into the engine bay and the earth problem at the steering column knuckle?
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BenHar
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Wed Mar 27, 2019 1:00 pm

Pretty common, yes.

eg. viewtopic.php?f=2&t=261096&p=2838797&hi ... g#p2838797

If you had done Brian's test, the next thing he would have told would be check the column bearing earth.

It's always worth using the search function on here before asking a question or paying someone.

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Billy1972
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Wed Mar 27, 2019 1:13 pm

Thanks Ben and Brian your experience is valued to a total E30 novice like me and I do appreciate it.

Do you have a photo, part number etc of the exact part I need to replace so that I can eliminate the temporary fix?
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Brianmoooore
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Wed Mar 27, 2019 1:25 pm

No parts needed whatsoever to cure the problem, which is that the bottom bearing of the steering column has dried out and the balls of the bearing have become coated in an insulating layer of hardened grease.
Squirt something like WD40 (other rust releasing fluids are available) up the column from the engine bay, and 'exercise' the steering. Repeat until the horn will sound (ignition on and horn button pressed) while the steering column is being rotated, with no drop outs at all. When the WD40 has all dried, follow up with some spray grease.
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Billy1972
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Wed Mar 27, 2019 3:20 pm

Sorry Brian I'm going to sound right thick, but are we talking about the same part? Its at the base of the column in the engine bay down by the manifolds is where the column has a mushroom shaped joint and it's a wire my guys has by-passed either side of it to make an earth. I'll take some photos when I drive it next to show you what I mean as spraying up the column seems wrong when the problem of the bad earth seem below it in the engine bay. I know you know what you are talking about its just me being a novice I guess.
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Brianmoooore
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Wed Mar 27, 2019 6:21 pm

The column isn't earthed by any wires. It's earthed through the ball bearing right at the base of the column. The bearing is actually in the passenger compartment, but the tube is hollow at the bottom end, and accessible from the engine compartment.
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BenHar
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Wed Mar 27, 2019 6:41 pm

Billy1972 wrote:
Wed Mar 27, 2019 1:13 pm
Thanks Ben and Brian your experience is valued to a total E30 novice like me and I do appreciate it.

Do you have a photo, part number etc of the exact part I need to replace so that I can eliminate the temporary fix?
Did you read the page I linked to?

It explains what you need to do.

Ben
Billy1972
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Tue Apr 02, 2019 4:27 pm

I did read the link and here is a photo of the temporary earth which has been put in place to give me a working horn. So do I need to buy a new knuckle section?
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Knuckle (1).jpg
Billy1972
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Tue Apr 02, 2019 4:30 pm

Brianmoooore wrote:
Wed Mar 27, 2019 6:21 pm
The column isn't earthed by any wires. It's earthed through the ball bearing right at the base of the column. The bearing is actually in the passenger compartment, but the tube is hollow at the bottom end, and accessible from the engine compartment.
This is the temporary fix my electrician put in place, how I'm explaining how he's bridged the earth does that make sense now?
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Brianmoooore
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Tue Apr 02, 2019 5:16 pm

NO!!!!! This is what you get when you trust your car to people who don't understand what they're doing and how they're supposed to work. You're now earthing the horn through the precision surfaces of the rack, which isn't good for it.
The bearing that's causing the problem is just to the left of your pic. Squirt contact cleaner or rust remover into the hole where the steering shaft comes out. and when the horn is working again, squirt some spray grease up as well.
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