Horn not working.

[MickAP]

Had a problem in the past with the horn not working, then it's all ok again when the ignition is turned off, then back on. When it stopped working before if pressing the horn in (without it sounding) the radio volume would increase, weird! Now when this has happened before switching the ignition off and on again seems to clear the fault. Now it doesn't clear at all just no horn but the radio volume increase still occurs when pressing the horn.
All other controls work normally on the steering wheel except the horn.
Anyone else had this problem, could it be an earthing fault due to the weird volume increase when the horn is pressed, or some other contact faulty?

BTW '06' plate Signum

Mick

[DSS]

I don't understand the radio bit but the normal fault of the horn not working is that the horn connection is the usual fault as they soon get wet and dirty being in a low position under the car.

sometimes cured by cleaning the corroded connection.

[MattVecVXR]

It sounds like a common CIM fault, have you done a search?

[rich r]

Sounds like the CIM is seeing the volume button being pressed rather than the horn button. Possibly the horn wire has come off or the loom got crushed so the wires are touching.

Or maybe the CIM itself has developed a fault internally.

[MattVecVXR]

The CIMs had a habit of randomly throwing a wobbly and the first symptoms would be with the horn, either controlling the radio or not working when the dipped headlights were switched on.

[MickAP]

Checked this morning and the horn still not working. Every other function is ok except the radio volume goes up when the horn is pressed.
As a joke (I think) my other half said,
"try the volume control on the radio, the horn might sound"

Anyways if I remove the horn/airbag cover will it reveal wiring that I may be able to detect a fault with? Where is this CIM module? and can it be checked, or dealer job?

Apart from checking the obvious like fuses and of course the horn connections does this sound like the faults at the steering wheel controls? I think so. I've seen the how to on removal of the airbag stuff etc.


Mick

[rich r]

The CIM is at the top of the steering column - effectively what the stalks plug into from the sides.

It might be worth unplugging the steering wheel connector from the CIM, and using a multimeter or test lamp to check what happens when you press the various buttons. I don't have a pinout for the connector, but it shouldn't be too difficult to work out. That way you can find out if it's a steering wheel fault or a CIM fault.

[MickAP]

Well the horn is working again.

Took the centre of the steering wheel off complete with airbag only to find nothing visually amiss. There is a spring which looks like an earth point for the centre part of the wheel so I bend that up a little and it's contact point then stuck it all back together. Reconnected the battery and the horn now works.
Don't know whether it was doing the above or just disconnecting the battery has reset something, who knows but we are working again. Spanner light came on and stayed on but went off after the first restart.

Thanks for all the help and suggestions.


Mick