Laredo Transmission Woes

94 JGC Laredo 4.0, 4X4 automatic, 201,000 miles, 90,000miles on factory reman transmission which has been flawless. After sitting unused for three weeks the transmission was slow to engage (start moving) when shifted into reverse. The transmission starts in high gear and remains in high gear. The OD light will not show when the OD switch is pressed. If the selector is placed in 1 the transmission will be in 2nd gear and will shift to 3rd when the lever is manually moved to Drive. OD will not function. The transmission fuse in the dashboard panel is ok and the 15amp transmission controller fuse in the engine compartment is ok. Techs in two different transmission shops get no communication from the transmission using their analyzer plugged into the transmission port accessed from the interior transmission tunnel. The fluid is at the proper level and is red with no smells and no discoloration. The on-board fault code shows the normal 55 with not fault codes. Any suggestions will be sincerely appreciated.

How is the fluid level in the trans? These are sensitive to low levels of trans fluid.

after this 3 weeks ,your batterie was discharged???