New to this forum,
My son has a 03 Super duty CC King Ranch,6.0 5r110 trans. It has 133k miles
He is running a STC ? tuner 4" exhaust and a Powermax turbo.
It started with a shutter in reverse, then it would slip or neutral 2nd and 3rd it wont go into overdrive, and the tow/haul light flashes.
We have removed the tuner, same thing. Tried to relearn, works cold to some degree, then back to same problem. Have changed both filters and proper fluid. Codes P0603 P0730 P02703. He has cleared them all but P0603.
Shuttering in reverse is likely the direct clutch is toasted (hence your P2703). You could also have a stuck intermediate solenoid (different issue from direct drive). Will it shift into 6th? Or converter wont go into lockup? Canned SCT tunes are not kind to these transmissions. The P0730 is a gear ratio error. The trans needs to be rebuilt. If you are interested in doing so, shoot me a PM.
It will not go into the top gear, 6th or we thought o/d. He said it slipped all the way to work this am. Put the 80 hp tune back on, no real difference, hoping it will re learn.
We are located in Kansas. Thanks