I've got a 2003 Dodge 2500 Cummins. A couple years ago it dropped the front drive shaft and ruined the transfer case. A replacement was purchased from a wrecking yard and installed. Everything was fine. Recently, while shifting from 4x4 to 2 wheel drive, the indicator light in the dash started reading backwards. Now when I am in 2 wheel drive, the 4 x 4 symbol in the dash is lit. When I am in 4 x 4, the light goes out. Any suggestions and what to look at?

 

Have you tried putting it in 2wd then resetting the pcm?

 

What is a pcm and how do you reset it?