960 (1997 Model) Alarm System Problem

[Puddinghead]

Firstly let me thank you all for solving a minor coolant loss problem which was , as suggested , small leak behind water pump.
Cannot send thanks personally due lost info after change of computer.

Problem has now developed with the alarm system . After locking with key fob after a few minutes alarm goes off. ( At the moment lock car with key which operates central locking OK)

All doors fully locked etc and no one touching the car.
I suspect a faulty sensor somewhere. I am sure I can fine them all but can someome please tell me how to check them.
For example , if I disconnected them one at a time will this prove one of them faulty.
Is this the way to go?

Thanks

[Puddinghead]

I have been advised elsewhere that disconnecting one sensor stops all working , so back to square one.