I am up in Watford City ND working right now and the other morning I went out to my truck and I had no revese. Also when I accelerated the truck seemed like it was pulling a hugh load. I also had a check engine light which is new. Anyways after a 50 miles of driving it was still doing this. I parked my truck and left it run for 3 hours thinking something was froze up because we had night time lows of -10. Still no luck at first and then it began to work again till tonight I have revese still but it seems to have a load on it. I have checked the fluid and it is up. I think maybe it is slipping? The tranny has been dropped once for the Oil leak the truck had probably 35000 miles ago. Oh tonight I also had the message " Shift to N to reset transmission" or something like that. Any help would be great! Oh and I have aditive in my fuel and keep it plugged in at night.
I really dont want this to strand me in ND I have to head home to NY Monday........ 1600 miles.

Check your fluid level.

Put it in the middle of the HOT band as checked at 175-180F trans temp with the engine running, trans in Park. It will be lower if the sump temp is not that warm.

PM Mike L. or call him
Inglewood Transmission Service
714 870 7300 Shop
He'll get u pointed in the right direction!

Need codes asap. Do not keep driving while Alli is in default. Could be something as simple as F trim solenoid failure.

On star said the codes were something to do with the pressure switch. They said there may have been so air in the system creating a problem. They said to drive it for a day or two to see if it works way out. Either way today the light is out and everthing is working okay.

Oh and thanks for replies!

Sounds like you're losing pump prime/main pressure. Most common cause is low fluid or thick fluid in cold temps, the fluid level draws down in the pan then the pump sucks air in through the suction filter.

Typical codes set are P0701 along with any or a combination of codes; P0751, P0756, P0761, P0843, P0848, P0873 or P0877. The latter codes are coming from the pressure switch manifold, but due to the loss of pressure.