jrs26

Hi all I am new here just bought a 2007 equinox LT AWD and immediately started experiencing problems. Speedometer would quit working transmission would shift hard especially between 3 and 4 and down shift hard rpms would jump up high between shifts. The stabil track light came on and put the vehicle in limp mode. The mil cam e on I retrieved 2 codes $7E8 transmission control circuit failure to communicate and $7EA transmission control system, according to my coder reader. I replaced the output transmission speed sensor (oss) cleared the codes speedometer works intermittent like before trans shifts great when speedo works but when it stops it goes to nuts. I have not gotten anymore codes out of it I did have the key issue a couple of times I couldn't start then had the key stuck in it a few times. I checked ground connections connectors on tcm, ecm, bcm and replaced the tcm with a used known good one vehicle acts just like before. Occasionally when I start the car the speedometer will show a high speed like 80 then start going backwards, it did this before and after all the work. Anyone have this issue before? I am thinking its in the bcm but not sure, also any one know exactly what sensor the speedometer uses to calculate vehicle speed? Any help would be appreciated.