The 2005 Lincoln Navigator features a keyless entry system for locking and unlocking the vehicle's doors and lift-gate. In addition to the key fobs provided with it, there is a keypad with five control buttons located on the driver's side door. It requires that you enter a five-digit personal code in order to unlock the doors. It comes with a preset code from the factory, but you can reprogram your own.
Open the front passenger side door. Locate the fuse panel cover on the right side of the passenger foot well, near the door.
Pull the cover off of the fuse panel. Locate the module label that is above and to the left of the fuse panel. The code is in large, bold numbers on the module label.
Record the number on a piece of paper for future reference. Replace the fuse panel cover. Enter the code into the keypad to test it. The doors should automatically unlock.
