Sticking horn

[Eddie Nuff]

The horn is stuck on on swmbo's C4GP so the airbag has to be removed from the steering wheel hub to get at the ring where the horn contacts are. When pressing the screwdriver into the hole underneath the airbag springs up a small amount but will not pull out, as though it's stuck on the mechanism that holds it onto the wheel.

Any ideas on how to release it completely as it's annoying that it's so near and yet so far from completion.

[RichardW]

I'll have a look later, but this may well not be a fault at the wheel - don't forget these are multiplexed, so the switch sends a signal to the BSI (and / or) the underbonnet fuse box, and then in one of these locations, a relay actually powers up the horn. If you could get it on diagbox you should be able to see if the ECU thinks the button is pressed.

In fact I have a dim recollection that this has come up before....

[RichardW]

It just says:

Insert a large flat screwdriver in the orifice " a".
Push on the pin ( 2)By means of a screwdriver.
Unclip the airbag ( 1).
Disconnect the airbag ( 1).
Remove the airbag (1).

Where a is at the bottom of the central hub. Perhaps you just need to push harder!

[RichardW]

And the wiring diag shows it going via the BSI to the underbonnet fuse box, where the relay is located to actually power up the horn.

[Eddie Nuff]

Hope to have my Lexia back up and running by the weekend so I'll see what it throws up. I've removed the fuse as it's a hell of a din, will it have to go back in to test the circuit?

I've pushed in every way, shape and form but it won't release after the initial pop out of the wheel base.

[RichardW]

Don't think so, Lexia will hopefully be able to tell you whether it thinks the button is pressed or not. When does the noise come on? If it's all the time, then it suggests independent of the BSI, and fault with BSM. If it goes off when the BSI goes to sleep, then perhaps fault with BSI or COMS unit.

Edit: In this thread, Wheeler implies (on a berlingo at least!) the horn is not via the COMS unit. I'll have another study of the wiring diagram...

[Eddie Nuff]

The fuse is out for a reason - it's either that or the earth lead to the battery. Otherwise it would be on ALL the time.

[RichardW]

Duh, failed on the link: viewtopic.php?t=30650

Actually I can't remember, maybe the hornworks irrespective of the status of the BSI? I'll check. I'd be leaning towards a fault on the underbonnet fuse box.

[GiveMeABreak]

Do we have your VIN for the C4GP? I've been looking at the wiring for a 2008 C4GP and the horn is linked to the bonnet anti theft pin and then to the interior protection. Fuse F8 on the BSI Fuse Box I think controls this - but can't be sure without your VIN.

[Eddie Nuff]

I'll post the VIN later this aft.

[Eddie Nuff]

VIN: VF7**************[VIN obfuscated, can be read by forum staff]

2008 1.6hdi

[GiveMeABreak]

I can't attach PDFs here, so I've emailed them to you.

I've put a guide together for the codes here:
https://www.frenchcarforum.co.uk/wiki/E ... ring_Codes

[Eddie Nuff]

Thanks Marc. that looks like real fun.

[GiveMeABreak]

Aren't they always! Just thought that they may help you trace the connections from the horn to the relay and fuse in case there is anything obvious there.

[RichardW]

I had another look - seems to me to be 'soft' operated via the BSI / BSM. My money is on a fault with the BSM. I have a got a spare which will probably fit, and I think is OK - I bought another chasing a handbrake fault that turned out to be the EGR valve!!