Volvo VN 2012 Quick Reference Manual page 8

cab doors, door locks and keys
Door Locks
The door locks are mechanically or electronically operated. The lock is
activated by the key from outside the truck, or by the door lock handle from
inside. With mechanical locks, only one door can be locked and unlocked at
a time. With electronic locks, both doors can be locked and unlocked by the
key or by the inner door lock handle on the driver's and passenger's sides.
Note: Neither door can be locked while it is still open. The door must be
closed for the lock to work.
8
Mechanical Locks
With mechanical locks, to lock either
door from inside the cab, push the door
lock handle forward. The handle will stay
in place, indicating the door is locked.
It can be unlocked without opening the
door by moving the door lock handle to
the middle position.
Pull the handle back to unlock the door.
Push the handle forward to lock the door.