This is a real problem, since I have tools in trunk. I'll have the neighbors call, or just go out and find, my trunk open.

I'd be very happy to just disable the fob trunk release. It'* too dangerous to have the trunk open anywhere, anytime.

Suggestions?

Pull the battery from the FOB to eliminate the FOB as a suspect first.

I would also consider that the latch may need a little adjustment and is not really latched secure. Vibration while driving may then let it work free and gradually lift, perhaps aided by wind currents while parked. I have also occasionally found that fob buttons were being depressed by other keys or coins while in my pocket and unlocking doors.

Excellent idea. I've found that when the battery begins to die in fobs for Chrysler vehicles, the fob will send a signal to the vehicle to lower the windows and unlock the doors. Newer Nissans will pop the trunk and unlock the doors. Newer Hyundai'* will pop the trunk and beep the horn.

Maybe GM has incorporated some type of feature into thier system as well.

Just disable the latch in the truck..pull the electrical connector or move the on/off switch to off(if it has one).....