07 equinox shifting problem.

Hi I have an 07 Nox that will shift rough until it reaches 4th or 5th gear. Once it does it will not downshift, the only way to get it to down shift is to put it in park shut it off but it just goes through the same cycle again. Its throwing a P0405 EGR low voltage, P0706 transmission range switch performance, P0982 Ss4 control circuit low voltage. Maybe a bad wire or harness?