Jeep GC wont go into O/D

I posted this in the Jeep forum, but never got an answer.....So Ill try here.

My 94' Jeep Grand Cherokee Laredo 4.0 all the sudden does not go into O/D. I tried cycling the switch and I dont get a light at all to show it on or off. The vehicle has about 213,000 miles on it but has been well maintained all of its life.

I noticed the problem when getting on the expressway and not having any speed. It felt like it was in high gear and it the power was gone. If I roll away from a stop and shift manually it acts fine, except it will not go into O/D. I believe the default setting for this trans is 2nd 3rd gear, and maually you can shift from second to 3, but not O/D. Im not sure if I should look into my solenoids in the trans (Gov and TCC or O/D) or if theres something else common to check...not having any response from the O/D switch somewhat raises a concern.

Ive checked the fluid and all looks well there. I am going to investigate the fuses in the PDC tonight and attempt to get trans codes, though as I understand it it flashes the O/D light...which isnt coming on currently, so I dont know if that will work. Any help is appreciated. Thanks!


::::UPDATE::::
Last night found that my TCU fuse was blown. If I replaced it my O/D light came back on and the trans shifted and acted normally. After I went about a mile, it started acting up again. Pulled over and found the fuse was blown again.... Is the TCU itself problematic? Does anyone have a diagram showing power feeds for this circuit?? Thanks

I don't know the wiring on your vehicle but I recently dealt with a similar concern on a Ford that the manual showed the only thing on the trans fuse was the trans it self, I found that the fuse would blow on this vehicle with the tans connector unplugged... Eventually I figured out the rear O2 sensors were also powered through the same fuse.. And water had shorted out a sensor...

i've got a jeep gc with the 5.2 and have had some trans problems similar to yours. first time i hit a big pool water on the highway and the jeep shifted down, wouldn't go into od. found that the plug had been slightly pulled from the tranny and water had got in. we pulled it off, blew it out and di-electric greased it. this winteri had to drive over some mounds of snow, after nyc sanitation plowed me in and the tranny did the same thing. again we pulled the plug, blew it out with air and di-electric greased it. took a plastic tie wrap and tried pulling the plug into the trans to hold it there. seems to be working but i've never blown a fuse. upon closer inspection i found the plug, in the tranny i guess had cracked from the 1st time i hit the water and partially yanked the plug, the reason for the tie wrap. just my experience. dave