Alarm system and door locking mechanism

[PeterK]

My new to me, 2001 Boxster appears to have some malfunction in the alarm system.

I can lock both doors with the fob. When I manually try to lock both doors with the key only the drivers side locks.

When locking the headlights are not flashing nor is the horn chirping.

I can unlock the drivers door with the key but it only unlocks the drivers side and not both doors.

Finally, and this is new, when driving I can hear the doors locking and unlocking at random. The courtesy lights ( dome and door lights )come on in the middle of driving.

Any quick thoughts come to mind ? or do i need to replace the locking mechanism on the door. Also, when replacing the locking mechanism do I have to rekey or reprogram the whole unit ?

[JFP in PA]

Look at the immobilized/alarm system/locking system control unit under the driver's seat; if it shows signs of being wet (corrosion), that is your problem.