2000 Cadillac DeVille, Valet 552T

I own a 2000 Cadillac DeVille and have an issue that may be an easy fix, how ever I have been out of the mobile electronics loop for a number of years now and seek some assistance. If the DEI my valet alarm is armed before one of the passenger doors have been closed, the next time I dis arm the alarm and open the driver's door, the factory alarm sounds without the ability to disarm/disable it by using the driver's door key lock. Any ideas any one? Thanks! StargaizerStargajzer

Why would you want to arm it before the door has been closed?

I don't do this intentionally, the children some times are slow to close the doors of the car, and at times they do not close them completely, and my wife may not always notice this before re arming. Any how this is irrelevant, there is an issue that requires attention as it should not perform in this fashion. Thank You.Stargajzer

Maybe the switch on the back of the keycylinder is broke?

Can you NORMALLY disarm the the alarm with the drivers door key?   With the drivers door open and window down, press the lock switch on the door, close the door, wait till the fact alarm arms then reach in and open the door with the handle, alarm sounds, can you turn it off with the drivers door key then?

Have you tried unlocking the passenger door, does that turn it off?  It should.

Is there a disarm wire listed for that vehicle, maybe inside the door?