I accidentally set my disco's alarm off the other day (only had her a week) and although the lights flashed there was no siren. After a bit of research and grubbing about under the bonnet I've found that the wires going into the sounder have been cut. After a bit more research I realise the likely reason for this is because the alarm got stuck in armed mode and kept going off. Now I'd rather like to reconnect the sounder, or fit a new one, as an alarm's not much use without it but am concerned that if my suspicions are correct then it'll just go mental as soon as it's re-wired. Does anyone have any advice on how I can either check the ECU for the "armed" state and reset if it is armed or bypass it in some way? I don't have the fob (ordering a new one from Remote Key) so it's currently working on doors locked with key basis.

Also on the subject of security, does anyone have any recommendations besides a clutch claw? I wanted something like hubby's X-Defend that locks the two gear sticks with the car in gear but can't find anything to fit a disco. Thought I might try and recreate the effect either with a flipping huge padlock or a length of heavy duty chain.

The year of manufacture of your disco will help as there as two types of alarm systems in places do identified by the number of buttons the fob has, if your system has a two button fob and as u say you don't have a fob then then there has been some modifications to the security system, you shouldn't be able to start the engine without the fob, also as u say u have found the wires for the sounder was that behind the front grill or on top of the offside front inner wing which is the position of the electronic sounder if you had one.

With the early single button fob you can set and unset the alarm and immobiliser via the key in the drivers door lock, this system has a horn style sounder behind the front grill.
If your alarm system is set it would activate every time you opened the doors via the central locking system.

Ah noob error! I have a 1994 M-reg Disco which would have a single button fob according to both the owners manual and Remote Key - the Lucas type I think it's known as.

The alarm sets and deactivates with the correct key in the door, which according to the owners manual means the volumetric alarm inside isn't being set - another reason for a new fob! I set the alarm off by unlocking and opening the tailgate without unlocking the doors. Once I've unlocked the doors with the correct key I can start the engine fine.

The sounder looks like a horn style one with some electrical type gubbins underneath and is located on the offside wing in the engine bay. Since its not connected to anything I'm tempted to remove it for a closer look.

Seems that your in luck and the alarm system is operating correctly other than the missing alarm sound.
Soall u need to do now is find the pair of wires that originally went to the sounder and connect the wires to the terminals of the sounder, if your luck is still holding it will give a noise when the alarm is activated and then silenced when it does remotely with your new fob, or unlock with the key in the mean time.

I might have hit another snag. If the thingy I think is the bonnet switch IS the bonnet switch then it too has had its wires cut.

The thingy in question is on the right. Now if this is the bonnet switch I'm guessing it might be faulty and might be the culprit for the sounder wires being cut. Or I might be clueless - either is possible!

Snagette no 2 is that I have no idea where to wire this lot back up to and my trusty Haynes manual doesn't have wiring diagrams for the alarm system (for obvious reasons I suppose). Surely it doesn't just go to the main battery - wouldn't that make it ridiculously easy to disable by thieving scum?