Are all of the vacuum lines hooked up / in good condition? I had a similar problem with my 2000 Cummins 2500 4×4. The vacuum lines got pulled off the actuator at the front axle.... just a thought.2001 Ram 2500 with 47RE and 241HD transfer case. I put it in 4 wheel drive and the passenger side spins but the driver side doesn't, front and rear. I've been OK replacing many parts on this truck, but not sure about the transmission and transfer case etc if I'm ready for that. I have searched using "make and model + 4x4 works one side only" but but nothing solid was found. I don't know much about the wiring and vacuum line side of things.