Horn always on (not a jammed button)

[Lenroc]

Hi

history of the problem.
My car was working fine, except central locking boot locking; the only actuator that worked when locking/ unlocking was the fuel cap actuator
They are all on the same fuse (fuse 16 on my ZEE fuse box). Since horn was also on that fuse and since the horn was working fine, I thought that the actuators might be all dead (slim chance, but they never worked ever since I've got the car)
It did not bother me as I do not normally lock the cars anyway

Yesterday however, my horn started to sound while I was driving for no apparent reason. I have checked the horn button on a steering wheel and that is not jammed

I had to take the fuse off, and now I have no horn no central looking
the car works fine, the unlocking disables the immobiliser so I can use the car like this; except it is due an MOT

I need to get it fixed, and I do not know where to start;
the facts are, horn is triggered from somewhere else, but I have no idea of the layout of the wiring diagram for horn is
I believe that some sort of faulty alarm, faulty locking actuators, etc can trigger the horn
I will work my way systematically on this one but I would appreciate if anyone has any experience on anything like this

thank you very much

[mikerj]

https://www.evilution.co.uk/545

Check the main connector on ZEE is not suffering from corrosion and is fully plugged in.

[heinkeljb]

You could always wire the horn up with a seperate switch on the dashboard. As long as it is clearly labeled and easily accessible then it should be acceptable to the MOT man.

John

[mottofreee]

Replace Relay D.
The horn is commanded from the steering wheel. Remove the steering wheel cover (4xT10) and disconnect the steering wheel connector.
If the horn stops, then you have a short wheelbase (from a previous faulty repair).
If it does not stop then the fault is on the electrical path.
Has the problem been solved?

[Lenroc]

Yes; Just now I swapped the complete steering wheel with an older steering wheel I had. I have not identified where the problem is
I suspect that the steering wheel cartridge is somehow allowing a connection. I cannot think of anything else; I have checked and even disconnected the metal contact from the steering wheel
I will open the steering wheel cartridge in the future to check if it is somehow broken

[mottofreee]

I understand you've got it fixed by replacing the steering wheel.
When you break the spiral horn does not work at all.
Most likely the insulation of a wire is damaged.

[Lenroc]

Thanks
I just have the steering wheel opened and I cannot find anywhere the short circuit that allows the horn to always be on! i will keep trying until I will find what is wrong with this steering wheel

[Lenroc]

my Steering wheel Squib,( steering angle sensor unit- coiled ribbon) was melted allowing the 2 horn wires to touch each-other. lucky the 2 wires for airbag were unaffected

not sure if this was as a effect of the horn running for a long period of time (my wife had the car and horn started to sound in the middle of no where- it was an hour before I got there to remove the horn fuse)

or this (melting of the plastic ribbon) has caused my horn to run in the first place.

the coil seemed to be somehow jammed but I have had no problems with the horn nor with the steering wheel since getting this car
has anyone experienced this?
The horn, and door locks are on the same circuit (fuse 16 I believe)
ever since I got the car the door locks are not working (central lock is not working- when you press the lock unlock only the lights are showing no actual locking/ unlocking noise)
I thought it is unlikely that all actuators are burned, so I believe that there is something on that circuit, now with the horn becoming faulty.


WhatsApp Image 2018-11-10 at 22.28.41.jpeg

[mottofreee]

Steering wheel angle sensor has two jacks and the car is SAM.
Angle sensor & SAM are on Smart since with 2003.