adt 9600 alarm 1990 it was fitted?

I'm no expert... but you may need a new battery has it ever been changed in the last five years. The battery is usually located in the control panel box, which is quite large about 10in x 8in and a few inches in depth and usually has a small light on it, this could be in understairs cupboards/attics places like that. When you do find it be careful when you open it as it will go into tamper and alarm will go off be ready to dissarm it with your code.

Marie
February 2009