05 Dakota shifting into 4Lo by itself. What to do?

This is a common problem with the Dakota. The problem is one of three things. The transfer case shift motor, which is what actually shifts you from low to high. The hi/lo switch in the cab. Or it could be faulty wiring to the transfer case motor. If you decide to disconnect power to the transfer case motor, make sure it is not in low beforehand since there is no way to shift out of it once it is disconnected.

Since winter time, snowy roads, are FAST approaching your zip code .. Suggest having transfer case module 'professionally' scan tested so *live functional test data* can be viewed to aid in reaching a proven solution .. You may need to leave the truck with the repair facility a couple days to complete the necessary testing, which includes problem duplication and confirmation .. Good luck with the testing - and repair!