60valves

Let me preface this with; I have spent a lot of time reading trying to figure this out and learn from these forums. Having said that, this is my issue;

At the beginning of August 2018 I installed a rebuilt 47re into my 2002 Ram 2500 4x4. Everything went fantastic, beyond what I was hoping for, without any hiccups. Fast forward to Oct. 18 and my truck now has an issue. The trans goes into limp mode. With the cold weather the truck does it's cold start stuff, I let it run for 2 minutes, then put the truck in drive. The trans goes through the gears the first time fine. Get out on the highway and then limp mode sets in. Drive for a few minutes until the temp gauge starts to move. Pull to the side of the road, shut the truck down completely and then immediately restart the truck. No more limp mode!! The truck drives like normal. The only codes that have come up are P0753 & P1765. How can it be that it doesn't work cold but when it warms up the trans works beautifully? The trans is originally from a '98. It has a Standard Motor Products O/D&L/U solenoid in it p.n.~S9861 with the BD Diesel pressure transducer adaptor p.n.~1600365 and the stock '98 pressure transducer. Is there something in this combination that may cause the problem off cold start? The problem has only presented itself since the cooler weather has set in. I had found the first time a bad transmission relay so that has been changed numerous times with known working relays. Should I put the '00 and up transducer into the trans and see if that cures it? This transmission was in a previous truck and never gave a hint of an issue until now. I have also found that the alternator is on this circuit too and maybe with the cold start protocol the alternator is causing some interference with the trans? I would not make a post if I wasn't stumped.

Thank you for any help

AlpineRAM

Maybe you have the alternator brushes or a diode in the alternator going bad. For grins and giggles you can charge your batteries and then remove the 140A fuse for the alternator and do your test drive. If the problem vanishes rebuild alternator. If not, reinstall fuse, check the supply for the trans relay in the PDC, maybe a contact is worn. (especially since you seem to have removed and reinstalled the relay quite often)

Anything wrong with the pressure transducer would give you governor pressure related codes.

60valves

Thank you for your reply, what I have learned is that it is definitely during cold starts. It was a warm afternoon here yesterday when I left work, and the truck never gave me an issue. I will definitely give the alternator a what for. Thank you so very much.

AlpineRAM

No problem,

I think that you should clear the codes and then try to reproduce the problem, and look for codes again. This should enable you to see if those codes are related to your problem or maybe they were just an old fluke that kept stored.
In another thread I posted the measurements and pinouts to check if your solenoid is OK,and to check the wiring loom from the PCM to the transmission.

Find it here

60valves

Thank you for your help in diagnosing the issue. Turned out to be the wiring harness for the transmission. I changed the solenoid(o/d, l/u) and wiring harness for a known working piece and voila! Also changed the filter and did back to back testing of ATF vs Tractor Hydraulic Fluid(J20C). Long story short, new fluid(J20C) and new solenoid, the transmission is finally feeling fantastic!