99 Dodge Cummins Automatic Transmission - 50K miles on it. Intermittent problem with upshifting - fluid clean, no debris in transmission pan, changed oil & filter & replaced both solenoids, including governor solenoid. Took an additional 600 miles before problem reoccured. Transmission shifting fine for approx. 2 hr. drive, parked vehicle for approx. 45 min. At this time, vehicle would not upshift, no computer codes seem to be present, fluid levels good. Anybody have a clue?? Thanks. Glenn

 

My brother's 1991 does that also.

I read a fix for it in the 1st gen. form,...I think. There is something they either bypass..or hotwire..or something.

Mine did that but it was the sensor that is in the side of the trannty...and I think mine had a code, though...On mine, the sensor is on the drivers side of the tranny...I think back near the neck. Anyway, I replaced the part and it was fine after that.