Horn not working...

[BHadley]

Hi all, can some one point me in the right direction please?

1991 318is horn not working, have checked fuse 7 and its not blown, have removed horn and put horn straight on 12v battery and the horn sounds. (This is the one behind the front grill and the only one on the car I think)

I did replace the carbon brush behind the steering wheel as the old one literaly fell to bits but when tested with a multimeter I have 12v so a bit puzzled.

Don't know if it is related but the earth for the wipers was not good (as in not working) and moving it to the indicator stalk made it come back to life.

Thanks in advance for any help

[Brianmoooore]

Listen to relay K2 in the fusebox, while someone pushes the horn button with the ignition on. Does it click?

[Sanchez]

Sounds like your getting close to finding the fault.

Are the wires correctly attached to the steering wheel push button.

All 4 pot engines have one horn and 6 pot have two. Iirc.

[BHadley]

Thanks,

Brian moooore; I will check later today

Sanchez; its like the tech one style wheel with four horn buttons on the steering wheel so I can't see how it comes apart...

Will fix this, I managed to sorted the wash wipe issue this morning

[tari]

try pushing the steering wheel forward, relatively hard while your pressing the horn.

If it works, you have the same issue as me, which i still haven't sorted.

[Sasquatch]

the issue might be with the brass collar on the inside of the wheel. It is supposed to make contact with the sprung earth on the locking mechanism. You can try and unscrew it and lift it off the steering wheel with some folded pieces of paper. Then check if your horn works.

[Brianmoooore]

It might be this, it might be that is NOT the way to find a fault! There is a logical way to approach any electrical fault, and in the case of the horn, it starts with relay K2.
See if the relay clicks, then we'll know whether to concentrate on the primary or secondary circuit.









!

[Sasquatch]

It might be this, it might be that is NOT the way to find a fault! There is a logical way to approach any electrical fault, and in the case of the horn, it starts with relay K2.
See if the relay clicks, then we'll know whether to concentrate on the primary or secondary circuit.

!

Agreed, however I have had similar faults on the last 2 cars which both lead to me making a change to the bush under the steering wheel and though that perhaps this might be a quick answer to the problem.

[Brianmoooore]

The problem with random intervention is that you might make a working brush and ring into a non working one, and then end up with a horn circuit with two faults!

[BHadley]

Hi
Brian mooore;
Just to confirm of how to fix this horn issue,
There is no noise from the k2 horn relay and was tried with ignition lights on.

What would I need to be looking at next please?

[Brianmoooore]

Pull out the relay, and link pins 30 and 87 of its socket with a piece of wire, which will probably make the horn(s) sound, confirming that the 'power' part of the circuit is working.
Pull out one of the other orange relays, swap with K2 refit both of them, try the horn again, and if still no joy, remove the steering wheel.
Switch the ignition on, and use a piece of wire to connect the terminal of the carbon brush assembly to the end of the steering column shaft. If this doesn't make the horn sound, use the wire to connect the brush wire to a good body earth. The fixing screw for the interior light switch in the A pillar is probably the best convenient choice.
If the horn sounds with the wire to the end of the steering shaft, there is something wrong with the contact between the carbon brush and the brass ring on the steering wheel, or the switches on the wheel.
If the horn doesn't sound with the wire to the shaft, but does with the wire to the body earth, then the lower bearing of the steering column has dried up, and needs cleaning/lubricating. Easiest way to do this is with aerosols up the column from the engine bay, where the shaft comes through.

[BHadley]

Brilliant, shall try out whilst it is dry. Will update once horn working as it should. Way more to it than I first thought!

Many thanks

[BHadley]

Pull out the relay, and link pins 30 and 87 of its socket with a piece of wire, which will probably make the horn(s) sound, confirming that the 'power' part of the circuit is working.
Pull out one of the other orange relays, swap with K2 refit both of them, try the horn again, and if still no joy, remove the steering wheel.
Switch the ignition on, and use a piece of wire to connect the terminal of the carbon brush assembly to the end of the steering column shaft. If this doesn't make the horn sound, use the wire to connect the brush wire to a good body earth. The fixing screw for the interior light switch in the A pillar is probably the best convenient choice.
If the horn sounds with the wire to the end of the steering shaft, there is something wrong with the contact between the carbon brush and the brass ring on the steering wheel, or the switches on the wheel.
If the horn doesn't sound with the wire to the shaft, but does with the wire to the body earth, then the lower bearing of the steering column has dried up, and needs cleaning/lubricating. Easiest way to do this is with aerosols up the column from the engine bay, where the shaft comes through.

Ok, so I followed the list from brianmoore and got the following ;

No horn sound from linking pins 30 and 87 from relay k2
Swapped over another orange relay, no horn sound
Removed steering wheel and connected a piece of wire from carbon brush terminal to steering column and the horn sounded!
I checked the carbon brush distance and adjusted to suit by spacing the carbon brush more into the brass ring and filed the end down square. but still no horn.

Removed brass ring and cleaned off all old copper grease someone had put on before me , offered up to steering wheel and attached a wire from the brass ring terminal that would have gone to steering wheel and the horn sounded but only when put to the left of the metal where the stalks mount. If i move the wire to the right nothing sounds .
A "repair" has been made with epoxy looking material, and my wipers didn't work on their original earthing point but did when I moved to to the indicator earth and all works fine.

What do I need to do now please?....... Seems like its very nearly there...

[Brianmoooore]

First of all, whatever pins you linked on the socket of relay K2, they weren't 30 and 87! Otherwise the horn wouldn't have sounded from the steering column.
If the horn sounded when you connected a wire between the carbon brush and the central shaft of the steering column, i.e., the bit with the splines on, then the problem is contact between the brush and the brass ring, or the horn push itself.
After that you've lost me! The earthing point for the indicator switch and that for the wiper switch is just two different points on the same bit of metal. This metal is NOT where the horn push earths.

[BHadley]

Thanks,
The fact that the horn sounded through the circuit was a relief.

Looks like new brush to replace the "preloved" part and a strip down and clean up of the horn pushes then.

thank you for the help.

[BHadley]

Fixed!
Did the bottom steering collom bearing clean up and oil a few times, started from scratch removed what was old chemical metal from apoor repair, couple with a dealer spec new carbon brush and its as reliable as it should be.

Thanks for all contributions....