Hello.
I hope y'all are doing well (obviously better than me right now lol)
Its a nice cold winter day in Canada and every ones cars are giving problems and keeping mechanics rich haha.

I went for a drive to the shop today in my 2008 Dodge Ram 3500 6.7 Cummins, stock except for DPF delete, EGR unplugged, Bullydog 40428 tuner. 375,000km / 233,000 Miles. very well looked after.
My truck drove fine for 10 minutes (minus -20c outside) then the problem arised.

From a stop, the truck would accelerate normal in 1st gear, then shift to 2nd gear smooth till 2400 RPM approx, 40 k/ph and fail to shift into 3rd. instead the RPM would increase rapidly and the truck would slow down.
from that point i would quickly take my foot off the gas to prevent over revving or hurting something.
i would come to a stop, then try to move again and this time the truck seemed to fail to get out of first gear and was very under powered, I turned off the ignition and then restarted it and the same situation would happen again... if I did not turn the ignition off, the truck would fail to accelerate past 20k/ph and pretty sure would not come out of 1st gear, very low power.

I returned my tuner to stock hoping it would solve the problem and tried to drive it again. exact same thing happened. then put my tuner back to tow/economy usual setting, same thing would happen.
DTC shows a P0700 MIL code. will take it to get a more in depth diagnostic tomorrow hopfully, as my tuner only gives basic DTC.

Any Ideas of what may be causing this?
I have spent most of the day researching and reading other posts that are simular but still a bit different to what i'm experiencing.

any help or insight would be appreciated.
thank you

 

The DTC is saying there is a code in the transmission module. You'll need to get the transmission module scanned to see any specific code and then more help may be provided.