I have a 01 2500 with 120k miles. My tranny upshifts and kicks down fine until it come up to temp. then I only get 1st and 2nd gear.My truck isn't throwing any codes and the check engine light is off. I'm well aware of the solenoid issues with the 46re so I replaced the valve body ,all the solenoids, and the pres. sol. transducer. Adjusted both bands and new ATF+4 fluid and filter. When I bought this truck it wasnt running and I've done soft resto on it which included a new TPS. Could my issue be a speed control sensor even though my speedo is ok? Or is my pump shot and am I looking at a total rebuild. I looked at the bands when I changed out the valve body and they looked like they weren't too worn and the old tranny oil was red with not too much snot in the pan.Also adjusted the cable from the TB. Please HELP.lol

 

There is an output shaft speed sensor located in the rear of the transmission
and there is one in the rear differential, the one in the differential works the
speedometer, the one in the transmission may need to be changed, it aids in
determining when to shift.

 

Thanks for the input RAMCHU. I replaced the speed sensor but it didn't fix my trouble. Before I spend any$ on a rebuild I wanted to make sure everything else was ok. I even tested my new TPS. .65volts at closed throttle and 3.65 at full throttle which is in spec. I even double checked all my grounds and made sure I had no wiring issues. I talked to a transmission shop and they said it sounds internal because it only messes up when it is up to temp. If anyone has any thing else I can try I would be very great full.

 

Need to plug in with a decent scanner, and see what various things are doing when the problem presents itself.
Output speed sensor.
Trans pressure sensor, (cross checked with a mechanical guage)
Vehicle speed sensor.

Something is getting hot, and failing.