Horn beeps when trying to lock

If I try and lock my car on the remote control the horn beeps and the car doesn't lock. Also if I try to lock the car by the key the same thing happens.

There are no interior lights on and I have treble checked that the doors and the bonnet are closed properly but the problem still exists.

Someone suggested pressing the switch in the engine bay on the bulkhead which I did but the horn still beeps.

For the last 3 days the car has been in the garage whilst they replaced the power steering pipe that runs under the front of the engine so the battery may have been disconnected for a while. Also I know they had a pig of a time with it due to rust and had to weld a nut back on. The alarm and locking worked perfectly before the car went into the garage.

Does anyone have any suggestions as to what to do next?

Thanks as always.

Is it the horn beeping or the alarm sounder with the double beep if the latter then is sounds as it the mislock beep indicating a door or bonnet is open, or in your case may be a faulty door/bonnet switch. Best to get the BCU piuged in and checked.

Was battery disconnected when welding ? and would have to agree with sounds like a door sensor , the bonnet switch is what i would have 1st said, there may be a way to bypass the bonnet switch ?

I had a similiar problem, and found that the cause was a split in the rubber on the under bonnet switch on the right hand side as you look at it from the front.

The bad news is you have replace the complete switch as the rubber is not sold seperately.or do a Heath Robinson.?

Thanks for the responses so far, some answers.

It is definitely only one tone.

I don't know whether the battery was disconnected. The clock was correct when I picked the car up.

I have opened and closed each door individually and on each the interior lights come on when the door is opened and go off, after a while, when the door is closed. Does the alarm use the same switch as the lights?

Can't see much on the bonnet switch but I have tried setting the alarm and holding the switch fully down but still get the tone and the car doesn't lock.

Ok one tone but which horn or sounder?
iYes It's same switch as the interior lights so if they are ok, so now looking a the bonnet switch not breaking contact when pressed just pull the plug to isolate, you may have an iffy ultra sonic interior sensor again just unplug or lock with the key to isolate and test.

Hi, I disconnected the bonnet switch and the alarm worked OK so I put it all back together and everything seems OK so maybe the switch was knocked when the garage were doing the work.

It possable I suppose anyway well done, you will know if it happens again.

Had this happen a couple of times, first the bonnet switch was faulty, just unplug it. New one is pretty cheap, just replace it.
Second time I inadvertently locked myself in, using the keyfob, then moved and set-off the volumetrick alarm! I unlocked and got out but I can't remember the sequence I used. Anyway, the horn and alarm peeped once every time I locked the truck by key or fob from then on. Bit embarassing at 3am.
Took me three days of trying to restore the sequence of opening and locking with the drivers door lock, passenger door lock and keyfob. It finally cleared but I am totally confused as to the sequence that succeeded. Good luck. All I am really saying is that there seems to be a sequence. If you muck it up it can be reset and you don't need to get it plugged in to clear it. I'm sure someone on here knows the secret.:scratching_chin:

I had the same problem when I collected my Defender from the garage after a service. Thanks to the suggestions above I checked the bonnet switch (I had checked all the door switches but forgot about the bonnet). The garage bods had managed to dislodge the switch so it was a couple of inches proud of its bracket. Luckily no damage was done when slamming the bonnet onto the switch. I pushed it into it's holder and the horn no longer double beeps on locking.

Nice bit of thread revival! (welcome to the forum by the way!)