Codes P0740, P0785, and P1860 being thrown?

Question

I have a 2000 chevy silverado 1500 LS with a 5.3L automatic. I have the codes p0740 p0785 p1860. When running and “driving” it has those three plus p0753 and p0758. It is stuck in 3rd gear and its in limp mode. I rebuilt the transmission and drove it about 45 mins to a friends house, everything was fine. Went to get back in it and drive thats when i noticed it was stuck in 3rd and the check engine light was throwing codes. I done everything right with the trans, so the first thing i thought to do was replace the transmission wiring harness in the rebuilt transmission, checked all the solenoids and they were fine. I started searching and seen that the ignition switch could be the problem by creating an open circuit. I changed that next, cleared the codes still the same thing. Then I unplugged the battery for a couple hours to reset everything as well, still got the same codes thrown. Ran the wires and checked for a broken wire, bare wire, or pinched wire but there werent any. Checked all the fuses both under the hood and in the truck, none were blown and there were power at those as well. Checked to see if there was power at the transmission plug (from truck) through the pink wire that powers the Solenoids it had 11 voltage. Not sure what else to do at this moment

Answer 1

checked all the solenoids and they were fine

How did you check the solenoids?

I never had that problem before but checking a national database of repairs for the same model, year, and codes, the most common solution for the codes was the solenoids, in fact, all the codes you have are related to the solenoids. The solenoids resistance may be checked fine, but the mechanical part of the solenoid will fail with time and usage, making the solenoids stick and setting the codes.

P0740 CHEVROLET Code - Torque Converter Clutch Malfunction
Read more: https://www.autocodes.com/p0740_chevrolet.html

P0785 CHEVROLET Code - 3-2 Shift Solenoid Circuit Electrical
Read more: https://www.autocodes.com/p0785_chevrolet.html

P1860 CHEVROLET Code - TCC PWM Solenoid Circuit Electrical
Read more: https://www.autocodes.com/p1860_chevrolet.html

P0753 CHEVROLET Code - 1-2 Shift Solenoid Circuit Electrical
Read more: https://www.autocodes.com/p0753_chevrolet.html