This is my girlfriends truck its a 01 dodge ram 2500 cummins and thought we figured it was govenor pressure solenoid so changed it took it for a spin and it shifted first to second fime now its back in second and won't shift at all the ony codes ots reading is glow plugs my only other guess is maybe torque converter but before i fork put 1200 bucks i need some other opinions please help me out guys!

 

Can you get readings from the trans as far as pressures? scanner should be able to show you what the sensors are seeing.

 

Hooked my code reader up to it and got governor pressure solenoid and torque converter overdrive solenoid! So i started replacing solenoids firt goemor solenoid cause its cheapest then overdrive solenoid as i was trying to het the valve body down for the overdrive something popped of the top so ended up pulling entire valve body off ended up finding that the boost valve retainer was broken(probably not the main problem but lucky find) and that her accumulator spring was also broken! So probably
Didnt have to go through changing all the solenoids but i would definitely urge anyone when replacing solenoids or anything internal on the transmission to pull valve body while youre in there if you havent had any work done recently and check it out thoroughly!