I need help with my truck

[The Promenade]

My '08 LE 4x4 seems to be stuck on 1st gear. The mechanic said it's a tranny issue with codes P0700 and P0731 showing. No biggie, we got it replaced.

but it happened again. This time he said this could be the brake, swapped the brake cylinder but the issue is still there. A friend said this could be a torque converter. I don't know what else to replace on my truck. At this point, I just want to sell it

 

[RtwoDtwo]

Maybe it's not a mechanical problem but electrical. It could be the Tcm, the wiring harness or the speed sensor. Have you checked that?

 

[Strata4]

Had something like this with my old ride, the transmission was acting up and stuck in gear, and it turned out to be a bad solenoid. Got it swapped, and she ran fine after that. I feel you though, sometimes it's just easier to cut ties and move on if it keeps giving you grief

 

[Piper and Perron]

You might also want to get a second opinion with a diff mechanic before you throw it the towel and sell it?