[CJM5]

Hi Horn stoped working all fuse o.k, code shows fault on steering wheel any Ideas what needs to be fixed?ouich

 

[CJM5]

Forgot to say year 2000 Large center airbag

 

[ger]

Your horn works by earthing a wire when you press the horn button (the airbag).

There could be several things wrong.

You could remove the airbag and check the earthing contact points are clean (probably little brass dots in the sprung frame).

The horn wire passes through a 'slip ring' which allows electrical contact whilst you can still turn the steering wheel.
Check to see if there's any electrical value (voltage) at the end of the horn wire with a multimeter - remember to have the ignition on. If not, I'd suspect the slip ring.

I think the earthing is through the steering column (so there shouldn't be a problem), but it could be earthing through a wire through the slip ring as well (so horn wire might be ok in slip ring, but earth wire isn't, so it's not earthing), I don't know without looking.

Slip ring is number3 in this diagram:
RealOEM.com   BMW E39 M5 STEERING COLUMN SWITCH

If you get a new one, double check the part numbers as the realoem diagram is off my chassis number, yours might be different (but I doubt it).

HTH.

 

[CJM5]

Had it apart today, all wiring connections look fine.

I continuity tested the pins from the back of the slip ring to the connectors on the front and it seemed to be ok.

I have read the error codes and I'm getting '81 - MFL Interface'

I have also noticed I have lost all the controls on the steering wheel, radio, cruise control, etc.

The back lights for the buttons on the steering wheel ocasionaly flicker when driving - but not often.

the airbag light on the dash is also illuminated but its dim.