P0717 Code, transmission in limp mode?

The truck listed above has an 8-speed transmission. This is an intermittent problem. Sometimes I can go a week without doing it, sometimes I can go several. It has been to a dealership (problem not fixed) and it has been to a transmission shop (problem not fixed). It has been doing this for 6 months now. When the check engine light comes on, sometimes a few starts and stops and it will clear itself. Sometimes I can go in with a handheld and clear it. The last time it cleared itself was when I unplugged the transmission connector to look it over and plug it back in. Now both shops said they have “checked everything” and didn’t find anything that wasn’t right. I’ve read this can be a ground problem for the TCM and some have tapped into the ground of the TCM and grounded it closer to the TCM by the headlight and it cleared up the problem. I would like to try this but I’m in need of the wiring diagrams for this truck and transmission. If y’all have any other ideas I’m all ears.

I don’t feel it's a mechanical problem (transmission hard broke) since it comes and goes and is intermittent. But I could be wrong.