Thanks Todd.
On the fuse issue, according to the owners manual, the same 5A fuse in the underdash panel controls the moonroof and the power rear window. The moonroof functions properly so I don't believe it is a fuse problem. The power relay box in the engine compartment has a separate 20A relay for the rear window. It was only about $4 for a new one so I replaced it but that didn't work either so I am pretty sure it is not a fuse or relay problem.
I also found this on page 75 of the owners manual:
Position recovery mode
If the motor loses position and stops mid travel, the motor will respond
to switch inputs by moving 0.6 in. (15 mm) each switch command in the
up direction only. Down will be a one touch down operation. If the
window is stalled in the down position and there are no other system
faults, the motor shall relearn its position and resume full functionality. If
there is a feedback signal loss, the window will remain in its 0.6 in.
(15 mm) travel mode with each switch command and will not recover
full functionality. This will allow you to ?inch? the window up to the fully
closed position. If the window does not operate correctly, see your dealer
for service.
As I stated in the original post I had previously removed the negative battery cable for ten minutes but that didn't seem to make any difference. However, after reading that info in the manual today I just went out and sure enough I was able to "inch" the window closed by repeatedly hitting the switch. As a matter of fact, I could stop it in just about any position up or down which would be a pretty nice feature if they had programmed it that way. What is interesting is that this happened several days ago but just hitting the switch didn't do squat until after disconnecting the battery. That is not mentioned in the manual.
Anyway, after moving the window to the fully closed position I shut the truck off and then when I restarted it the window wouldn't go up or down. But at least now it seems to be stuck in the fully closed position which is better than getting wet inside when it rains. I just disconnected the battery cable again so now I am hoping it will relearn the proper functionality when I reconnect it.
No dice. Still stuck in the closed position but at least now I know it is not a motor or fuse problem and I can drive it in the rain again. Maybe it just takes more time to "relearn"????