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