Alarm u/s... Help please

I have a 97 300tdi and the alarm doesnt appear to work. When the car is locked by remote, the indicators flash, but no light appears on the dash. If i sit inside and again lock it with the fob, it central locks but again with no red waring light on dash. If I then move around, nothing happens. If I put the key in the ignition, the hazard lights go on, the engine wont start, but neither the red light OR the alarm sounds. Any advice grapefully recieved.
Chris

check the sensors on the doors and bonnet. If a door or bonnet is partially open or the sensor is not working properly it may only partially arm the system. How long have you had the vehicle? The interior sensor may have been disconnected.

I've only had the disco 6 weeks. The POs have had mobile phone hands free kits fitted and partially removed (at least 4 ) so every where is just a spaghetti mash of wires. How do I test the sensors? Where is the interior sensor?