Horn won’t shut up!

[braincat]

Ok, so I disconnected the batteries on my 850 to give them each an independent charge, and when I reconnect them the horn sounds continuously. It’s never done that in 10 years of battery disconnection. To get going I thought I’d just pull the fuse (9) for now, but the horn still sounds when the batteries are reconnected! Then thought it might be something to do with the alarm, so I pulled fuse 18 for that, but it still sounds. Any ideas??

[Timm]

Try pulling Relay K2 - if the horn still sounds its witchcraft!

https://www.meeknet.co.uk/e31/Timms_...lay_Finder.htm

[braincat]

Thanks Tim, I’ll give it a try tomorrow when it’s a more sociable hour!

[cartoonz]

use the key to lock/unlock the door a few times, then get into the car and turn the key to "run"

[braincat]

Try pulling Relay K2 - if the horn still sounds its witchcraft!

https://www.meeknet.co.uk/e31/Timms_...lay_Finder.htm

Ok so it looks like I need the Witchfinder General! Horn still sounds continuously (not beeping, a continual blare), even with the relay pulled. I have a theory so I'd be grateful if people could go through it. I did the steering wheel mod from Tim's site to fit an e36 wheel about 6 or 7 years ago; never been an issue but with the cutting and splicing involved there's the possibility that there's been some wear and tear over the years and maybe the horn wire is touching another wire? So in essence it's feeding from a different circuit than it's supposed to, hence why the fuse and relay pulling is doing nothing. Is that a possibility?

[Timm]

Right, next remove K51 (if it is fitted) - if the horn still sounds there must be an alarm system that is spliced into the horn circuit - but make sure it IS the front horns that are blaring as there have been model variants that use a horn for the alarm. With K2 and K51 removed there is no connection to power of any kind for the front horns so don't worry about the steering wheel it is now completely isolated.

So, two possibilities: It isn't the front horns (under the radiator hanger) it is an alarm horn fitted somewhere else, OR the alarm system has been spliced into the horn system, OR witchcraft....

[braincat]

Ok so we can rule out witchcraft, pulling the fuse and the relays did nothing, but I left the horn going and the sound is coming from near the DMEs, so it must be the alarm system. Also, the engine refuses to turn over, so the immobiliser is active. It’s 100% not the CODE function as I never use it, plus the fact that the sound is continuous rather than on/off/on/off like normal is confusing me. Where do I go from here? I tried pulling all fuses and relays I could find related to the system but still nothing!

[cartoonz]

did you do what I suggested about 4 posts ago? Try that, it is the procedure to deactivate the alarm... use the blade of the key to lock/unlock the car a few times, get in and turn key to "run"

[braincat]

Yeah tried that, nothing.

[Timm]

The DWA system needs to be reset - and for that you need the boot (trunk) closed, bonnet (hood) closed, doors closed - and then do what Cartoonz says.

P.S. You are going to have to annoy your neighbours to get this sorted!

[Timm]

Forgot to say - there was a thread here a while ago regarding the horn - the DWA module has its own fuse (15A) and when that is removed the horn shuts up. There is a method of bypassing the DWA via its connection to the Body Electronics Module - I'll have a look for that thread

[Timm]

There it is: https://www.bimmerforums.com/forum/s...8#post30184648

[braincat]

There it is: https://www.bimmerforums.com/forum/s...8#post30184648

Now that, is a SUPER interesting read. Particularly because a couple of months ago my odometer and gauges stopped working, even though the alarm system was apparently fine, so I suspect something is afoot in the module itself. I'll have a look tonight when I get home. Thanks Tim, this could possibly be the holy grail.

[braincat]

Ha, culprit found, dwa module has a LOT of water damage! I’ve drenched it in electrical cleaner so I’ll see how that goes, failing that I’ll source another and see what happens. Thanks everyone who helped, let’s hope I don’t need to post in this thread again.
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