Car Alarms: QUESTION, nissan xterra, shock sensor

Question
I have a nissan xterra 2000 that I bought as is the owner told me that the car was running and shut by it self when running now I noticed that I can not deactivate the alarm of the car,alarm is factory alarm from nissan and I already tried too many things and still the same car does not starts the light on the alarm by the dash is always blinking I wonder if you know any trick for this kind of vehicle

Answer
Ok let's clear up the terminology glitch here.

1. FACTORY/OEM alarm = Part of the original schematics
and plans from the manufacturer.
(horn honk, head lights flash, Starter may crank and
die, no spark)

2. DEALER INSTALLED alarm = Just that. Once the vehicle
is brought to a dealer, the dealer sub contracts the after market
security out.
(horn might honk, siren and parking lights flash, starter kill relay,
no start, no crank, just dead.)

3. AFTER MARKET alarm: Same as #2 but you are AWARE that
the system was put in at the dealership, but may not
be informed of the brand name, or even what it's
total capabilities are.
(siren & parking lights flash, starter kill)

Which one applies to yours?

Either way, look at the past postings for
the following keywords/phrases:
starter kill, shock sensor sensitivity,
and valet/override, after market alarm disarm ,
to see the procedures
for your issue.

RM/ALARMTEK
CARALARMMAN.COM