selectrac problem

[richardkay624]

I own a 2004 Limited with 70,000 miles and am experiencing a vibration
from the rear of the vehicle only when in full time mode .
The vibration occurs between 40-45 mph and feels like one is riding
over "rumble strips". Any suggestions as to what might be the cause of this, and how much is this going to set me back?

 

[LibertyTC]

Without a proper inspection, It would be difficult to speculate what is causing this vibration. I find it curious that when you go into 2 wheel drive (rear drive) that the vibration goes away. This leads me to believe that it is not the rear that is the problem.
What I would recommend is that you take the Jeep into a dealership or known 4x4 mechanic, and let them do a driven test and complete inspection, to determine what "actually" is causing this problem.

 

[ShafferNY]

I would start by checking the transfer case fluid, but it almost sounds like there may be a problem with the differential within the transfer case, especially since it's isolated to only the full-time position.

If it were in other 4wd positions I would venture to say it was in the front driveline.