Theft Alarm Malfunction

[dlduscg]

When using the key to unlock the front passenger side door, the alarm sounds, without opening the door or any other alarm protected locks, and continues until I press unlock on the remote fob. All other locks operate normally, and the front passenger side door will set the alarm when locked with the same key. I believe it to be a faulty key cylinder switch, but since they cost about 100 dols, and the door must be taken apart, how can I be sure that it is not the actuator, LCU, or something else. Anyone know if the lock switch is electronic (transistor switch), or simply a mechanical device? There has to be some reason it costs so much, but if it is just an electrical/mechanical switch then maybe it can be just cleaned with a spray cleaner rather than replacement. Appreciate any input on this; first time in my 20 yrs as a Q owner that I ever ran into this particular problem.