I have a 2005 FX4
Today while driving on a dry road the 4 wheel low kicked in on its own , switch is still in two wheel drive. 4 wheel low lite is on as well , got the truck back home I assumed it might be electrical so I disconnected the battery. This however didn't do and good , after waiting over an hour I hooked the battery back up and it is still stuck in4wheel low.
Any ideas gentlemen ????????

 

Yikes, how fast we you going when low kicked in?
I don't know what would cause it to just jump into 4low, but there is a good sticky in the 04-08 section on how the system works. Might be worth a read.

 

Really don't think this is possible...I order to get 4L to engage you need to be in "N" and stopped.

 

Trust me it's possible it happened to me. The transfer case shift motor some how got energized and activated into 4low , the then bound up the shirt motor not letting it realise.
Freaking weird but it happened , I had to take apart the motor away. piece by piece off the transfer case to get it unbound .
After it relaxed I put it back together and everything is fine. Now I just need to figure out how in the he'll the motor energised in the first place.