Car Alarms: Prestige alarm goes off automatically, prestige alarm, valet mode

Question
My neighbors are complaining my car alarm goes off in the night. I have a Prestige alarm installed on a used Camry 99 model. Of course I don't have any manuals. The alarm did not seem to work when I bought the car over an year ago. I could use the lock/unlock with the remote but it made no sound - just the lights blinked. Then suddenly last week, it started making the sound with every lock / unlock. I said great good to have it !! But for the past 3 days the alarm seem to go off in the night. My car is parked in the back of my house and I don't hear it go off - but a few neighbors have complained - so I guess it must be going off.
I want to put it back to the no-sound mode as before or atleast want to know what the reason could be for it go off automatically.
Incidentally the car does have a loose battery contact and I have to fix the contact every once a while by just adjusting the battery terminals. This ensure the car can draw enough power from the battery for the engine start. Else it just shows dim display lights and the car does not start.

Answer
The shock/impact sensor seems the culprit here.
It's likely to be found under the dash area, blinking
when anything taps on the underpanel.
Locate and either unplug or turn down.
To simply disarm it, locate and use the
valet/overide switch.

To start, look under the dash area for a button or,
a toggle switch. When you locate it, turn on the
ignition key, press and hold in the button (little
spring loaded micro button, red or black possibly)
until the alarm chirps 1 time. This should over ride
the system, and only the keyless entry part,
if installed, would still be operating.
The LED (light emiting diode) light in the dash
should also go on solid.=VALET/OVERIDE

This stops the alarm except for the keyless
entry if installed. The next step is to
either remove the alarm or, try to identify,
and get new remotes for it.

But once in Valet mode, it will allow the car
to start and operate like there was no alarm at all.

Let me know how it goes.

ALARMTEK
CARALARMMAN.COM