09 GMC Sierra - 4.3L V6 and 4L60E - P0717 Code/Hard 1-2 Shift

[1wheelandunderpowerd]

Hello,

 

I have a 09 GMC Sierra with a 4.3L V6 and 4L60E that is RWD w/ 170k miles. I have a engine light that will come on that kicks out a P0700 and P0717. It seems like I need to replace the Internal Shaft Speed (ISS) sensor? I have hard shift from 1-2 every once in a while or when I am in traffic. Has anyone had this before? From what I have read, the ISS is inside the transmission behind the converter, is that correct? I am pulling up 4L60E manuals and I must be reading the wrong manuals because they do not show the ISS and only show the output speed sensor on the rear of the transmission. Is there a way to replace this without dropping the transmission (in which case I will probably have to take it to a shop). Are there other issues that could cause this code? I changed the transmission fluid/filter already and it looks good (no metal chips etc). I would like to avoid taking this to the shop if possible just due to cost, but it is starting to seem unlikely. I need to fix this soon because I need to get my vehicle registered in the new state I moved too (and I would like to avoid eventually destroying my transmission).

 

Thanks