Car Alarms: 1998 Mitsubishi eclipse keyless entry alarm, mitsubishi eclipse, hood pins

Question
The alarm goes off by itself and won't shut off.

Answer
If it is the factory alarm, I would have to believe you have a bad door pin or trunk/hood pin.  Unlock either door with the key to shut the alarm off if the transmitter is not working.  I would recommend looking at the door pins, and the trunk and hood pins to see if one is shorted or lose or just broken.  If you find it is the hood pin or trunk pin, I would recommend just unplugging it till you can have it fixed.  If it is a door pin unplugging it may work but that would require some more labor.