2018 Ram 3500 6.4 Transmission issue

[Smith921]

My truck has 99000 miles and the transmission has been acting up lately, it shifts great until you’re driving for about 15-30 min. Then when shifting from 1st to 2nd it jerks and then goes into limp mode 4th gear and won’t down shift until you come to a complete stop. My Truck dashboard says the tranny temp is anywhere from 170-190%.

Can anyone help before I take it to the garage

 

[2003F350]

I had this issue once long ago in a non-Ram product. Never did get the issue truly fixed, my guess is it had to do with worn clutch packs. They worked fine until the fluid reached a certain temperature, then it would start shifting hard.

It's hard to say what your issue is without collecting data from the transmission through the computer.

 

[deputy25]

My truck has 99000 miles and the transmission has been acting up lately, it shifts great until you’re driving for about 15-30 min. Then when shifting from 1st to 2nd it jerks and then goes into limp mode 4th gear and won’t down shift until you come to a complete stop. My Truck dashboard says the tranny temp is anywhere from 170-190%.

Can anyone help before I take it to the garage

My 2018 2500 was doing the same thing. Dealer replaced valve body and solenoid pack, pump, input clutches, and cooler. Thankfully it was under warranty. Running fine now.

 

[Big Payment]

Have you ever had it serviced? My trans temp never gos above 165

 

[mtofell]

Could be lots of things... my money is on the all too common valve body that seems to be the weak link on these 66RFEs as they age. I'm not sure about diagnostics and if/how to pinpoint the VB before replacing it.