Another trans. question

[Big Brute]

Hi guys, new member here got a question about the trans in my 01 Excursion. Truck is 7.3 4x4 139000 miles just got it back in dec. Problem is i'm getting the no shift between 1-2 shift unless i let off the gas,the o/d light was flashing last night,but no light today.Pulled some codes today P1000-monitor checks not complete more driving needed. P1211 ICP not controllable. This is the good one P0781 1-2 shift error (really) and P0732 gear 2 ratio error. The truck does have a Superchips programmer set on " heavy tow ". Previous owner had a camper, i'm guessing about 20-25 ft. no idea on weight,he pulled maybe 3 or 4 times a year. I pulled a 18 ft. trailer with 2 side by sides on it over the weekend with no issues untill i got back home. Any ideas would be a great help thanks in advance..

[Uncle Salty]

I'm no expert but your symptoms sound like a transmission with mechanical diode failure. My '01 F-250 has a mechanical diode transmission. I just hope it doesn't let go any time soon.