transfer case stuck lock in?

[3500 dually]

Hey guys I'm needing some good sound advice. The sight has not let me down yet. I have a 2003 GMC 2500 hd duramax and the transfer case seems to stay lock in. The drive shaft does not turn freely, I disconnected the front drive shaft and the axle is not lock in. When I do try to go in 4hi I can hear the encoder motor move and seems like its lock in but I get clunking noise from the transfer case. Seems like it is not all the way lock in and like its not unlocking all the way. This is a electronic shift transfer case. All the lights on the buttons are working find and none are flashing, I have no DTC's. Any help is much appreciated, thanks David.

 

[THEFERMANATOR]

1st thing 1st is check the fluid level. Pump rub is very common, and when the fluid level gets low, it is very common for the nylons on the shift forks to wear/melt, and then it stops shifting correctly.

 

[MrMarty51]

Now that is interesting.
I never knew that the newer T~Cases had a pump in them.
When did they start doing that ?

 

[3500 dually]

been very busy, i will check the fluid level tomorrow, I did take a glance at the case to see if it was leaking anything. i did not see any leaks. all is nice and dry.

 

[THEFERMANATOR]

Now that is interesting.
I never knew that the newer T~Cases had a pump in them.
When did they start doing that ?

When they switched to aluminum cases and started running atf, so mid 80's they started switching over.