Confused Power Locks or Alarm
 

I have an intermittent problem that has been driving me crazy. It has to do with the power locks and the alarm that I have. It seems to happen more often during the hot summer months, or when the truck has had a chance to heat up on a longish drive.

The problem is this, when I try to arm the alarm and lock all the doors, the alarm will arm but the doors will unlock. When I un-arm the alarm, the doors all lock. I can use the key to get into the vehicle, but the strange thing is that the factory door lock/unlock buttons are also confused so when I push unlock, all of the doors lock and when I push lock, all of the doors unlock.

The alarm is an Audiovox/Prestige alarm. I didn't install it, it came with the truck when I bought it. I have been digging through the wiring to see if I can find a poor ground or a loose connection that might be responsible for this behavior.

Since the door lock buttons get confused, I am wondering if it has nothing to do with the alarm exactly and is something to do with the factory security module or a switch or something. Has anyone dealt with anything like this before?