There is a delay when going from 4WD HIGH back into 2WD. I have to stop, back-up, go form D to N, etc. The problem is I never had to do these actions to get it out of 4WD HIGH. A few months ago, I could go from 2WD to 4WD HIGH at 55MPH and back to 2WD without any problem or delay. Now I have to stop the vehicle and do one or more of the actions previously listed. Is there a problem in the transfer case? The fluid level was full but I changed the fluid anyway. I checked the linkage, works fine, tight, moves freely, no binding, travel seems OK. What would cause this?

 

It is not really a problem with the tcase. It is just a design fluke. You don't have your vehicle info in your avatar, but I am guessing it is pre 91. Either way, the tcase has linkage that forces it into 4WD when you pull on the lever. However when you push the lever down, it will force the vehicle out of low range, but it is only a little spring in there that takes it out of 4HI. All the pressure has to be off the drivetrain to disengage. When you stop and back up, it reverses the process and takes the pressure off and then it goes out. You can also try letting off the gas or tapping the brake to do the same thing.