How should central locking work?
 

I have 1985 911 with a central locking question.

I can lock and unlock each door manually.

If the doors are both manually locked, the central locking light is bright red and when I press the central locking button both doors unlock.
If both doors are unlocked, the central locking light is dim read. When I press the central locking button, nothing happens, ie doors do not lock.
Should the doors lock when I press the central locking button ?

Every time you press the button, both doors are supposed to lock or unlock. When in the locked position, the button glows red. When unlocked, the button is not lit.

When the car's lights are on, the button glows dim red when the doors are unlocked. Press the button to lock the doors and the bright glows brightly.

+1, and if you forget or are too lazy to reach the button, you can use the manual knob to unlock the driverside door too :D,