Hi everyone! yes I'm new to this forum, hoping to get some answers, I'm working on my cousins 2002 Suburban, the factory alarm sounds when you open the door, doesn't matter if they are locked or unlocked use the key or the fob! been searching through the forums for a few hours now and all i see is alarm sounding when using a key. but this alarm goes off if you park the vehicle and leave it unlocked and open the when you return, 1 min or 3 days doesn't matter. right now just have horn unhooked and the lights just flash till its started but I need a fix asap! this thing is driving me insane! and no i'm a DIY not a pay a dealer guy.

 

might also add that I've tried resetting the system and everything mentioned in other forums already