Car Alarms: Car Alarm Malfunctioning, chevy blazer, passlock ii

Question
I read a previous question and it seems like my truck is having the same problem.  The alarm (i believe its factory because the horn honks and the headlights flash, and the security light goes on) will go off right after i park and turn the ignition off or when i try and get in my car unless it is armed a certain way.  If i lock the car and it doesn't do the two normal honks and a honk when i unlock it the alarm will sound.  It just started within the past month or so and i am not sure what is going on.  It usually happens when the car has sat overnight or been undriven for a couple of hours.  I have a 2002 chevy blazer.  Any help would be greatly appreciated.

Answer
Well there are 2, possibly 3 alarms at play here.
the first being the factory HEADLIGHT FLASHING, NOISE
GENERATING system. This has a wire you can ground to disable.
www.wirewerx.com for this info and procedure.

The next is the PASSLOCK II system. See the options at
www.GMPASSLOCK.com to see what can be done there.

Lastly would be the addition of an after market system.
This would be with a siren, knock sensor, and flashing
parking parking lights. If this is NOT what's happening, it may
be a bit costly to fix it.

Let me know if you can start the car in all instances.
Because if it the PASSLOCK II starting to fair, then you
need to get it bypassed soon or a visit to GM is next.

ALARMTEK
GMPASSLOCK.COM