Two problems related to automatic transmission floor shift have been reported for the 2003 Lincoln Navigator. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Lincoln Navigator based on all problems reported for the 2003 Navigator.
The transmission shift interlock has failed - effectively leaving the vehicle stuck in park while maneuvering the vehicle from a stopped position and attempting to move forward. This is the second time this has happened. Luckily, it was not in an emergency situation where we needed to move right away as indicated by a previous poster. For some reason, the transistor in the transmission shift interlock fails, effectively leaving the vehicle in park. As there is not a safety override switch that is handy, or a slot to put a key in the console to override the interlock - you are basically stranded. Per the owners manual, you have to remove a portion of the console with a screwdriver (potentially damaging it) and manually push a lever - in order to move the vehicle. This is rather dangerous, and I am now on my third one - there are no modifications to this vehicle.
The transmission shift interlock failed on this 2003 Lincoln Navigator. When it failed, it could have impacted the safety of both its passengers and the passengers of others around it, as it was in an intersection.