1993 discovery alarm

Hi, I have a 1993 auto discovery, it used to be a v8 petrol but know has a Isuzu 3.1 turbo diesel, this old thing gets used only a few times a year for a bit of towing, anyway the problem is with the alarm!! It will not crank and the hazards flash! I can get it to crank if I earthout the black and orange wire but the hazards kept flashing, the hazards will stop flashing after a few seconds but as soon as a drain is put into the system they start flashing again. The central locking is working fine unless I unplug the alarm! I only have the key no fob!