alarm flashing

I just bought a 96 tacoma reg cab.the last owner installed a jvc radio,it sounds ok I guess.If I open a door and leave it open for 2 long the lights start flashing.If I try to start the truck nothing happens but I can turn it off and back on and it starts right up.A friends says he thinks the security system is looking for the radio.Is there a way to turn it off...Thanks..

 

bump,bump...anybody out know anything about this???

 

what kiind of alarm system do you have?

 

factory

 

Just guessing here
It sounds like it is programmed to auto lock the doors after a specific time and since the doors are open it is flashing the lights as an alert that you have an open door

 

This truck is stock,No door locks.It does have air but thats about it...Thanks