well do you have manual hubs or automatic hubs? i'd say your hubs are shot... cause one tire should be turning since its open diff? or did ya put something in the front?
Sounds like you've got auto hubs since ya asked if there was a motor that engaged em haha. just convert em over to manual hubs, save ya lots of heartache, and you can just leave the hubs turned in, just make sure you have oil in the front diff, it won't hurt a thing.
93 ranger ext. cab 4.0L auto 6" SJ/custom lift--37" super swamper truxs M/T tires--lock rite locker w/ 4.56 gears up front--warn hubs--exploder 8.8 w/ disc brakes 4.56 gears and detriot locker--one-piece driveline--bushwacker cut-out flares--Bilstein 5150 shocks--2 10" xcite subs w/ 1600W Crunch amp-- tinted windows
waiting for: dual steering stabilizer, put on 3" body lift(in my room), dual shock setup, electric fan, possible SAS with a waggy D44