i have an 04 duramax, with allison trans. has a pressure control solenoid code p0776... clear computer... it shift all gears and works great, go about 1/2 mile, and it downshifts to 1st, sometimes looses reverse??, changed solenoids, still same problem. tried to read the file, it stops when it gets to the tcm part.. times out with 75000 error??? any ideas???