Dodge 2005 Ram Pickup 3500 - Manual (Page 18)

As a safety feature the doors will not lock when using the
door lock switches during the following condition:
1. The driver’s door is open while the key is in the
ignition.
Central Locking — If Equipped
Vehicles with security will have a feature called
ЉCentral
Locking Љ. When the key is placed in the door cylinder
and turned to the
ЉUnlockЉ position, the security will be
disarmed, the illuminated entry will be turned on and
that door will be mechanically unlocked. If the key is
once again turned to the unlock position within 5 seconds
of the first unlock, the remaining doors will unlock. If the
key is turned to the
ЉLockЉ position while all doors are
closed, illuminated entry will be canceled, security will
begin arming, and all doors will lock.
18 THINGS TO KNOW BEFORE STARTING YOUR VEHICLE