Central locking: What does the key do when you turn it?

[Red_Calibra]

For some strange reason, when I put my key in the drivers door lock and turn it fully to the left, the central locking motor in the passengers door makes a loud whirring sound.

If I only turn the key halfway/45 degrees, it doesn't make the sound. What exactly is the set up with the way you turn the key to lock? What is locked and what is different when you turn the key 45 degrees rather than the full turn?

My car is a 91 J plate 8v Calibra.

[V6_E]

Turning the key 45 degrees will just lock the car, turning the key 90 degrees will lock the car and activate the deadlock function. Sounds like the deadlock part is either playing up or on its way out. Get someone to sit in the car when you lock it and turn the key 90 degrees and get them to try and unlock the doors. If they cant then the deadlock function is working but if they can they its playing up.

E