Did a little searching on here but wasn't confident in which direction to start looking....

2000 Ford Ranger XLT 4x4 4.0L OHV 5spd Auto

I was driving home from work and everything was working normal. I pulled into the gas station and shut the truck off. It was never engaged in 4 wheel drive at all. Came back out of the gas station, started the truck and as I was backing out I could tell instantly it was in 4WD Low. The dash 4WD light indicator does not come on now when I switch from 2wd to either 4wd high or low, which worked fine a few weeks ago. The indicator light would blink about 3 times every once in awhile as I was driving the rest of the way home from the gas station at 5-10mph today. I've tried switching it, putting it neutral with brake depressed and switching, backing up a good distance, and it's still stuck in 4wd low.

What might cause this to instantly happen? Any help on diagnosing would be greatly appreciated!

 

The flashing lights means the computer has no idea what the transfer case is in. ie 2hi/4hi/4lo

Backing up will do nothing for your truck, that was for the older rangers.

Odds are the shift motor needs the be cleaned or replaced.

Servicing A Transfer Case Shift Motor

While you are in there you can see what the case is currently in and can shift back to 2hi if need be.