2007 Saturn Ion transmission not shifting. Also has a PO300 for over a year. Vehicle has 354k miles and was told transmission was bad. As I test driving I noticed speedometer was dropping to 0 and transmission was dropping out of gear. I wiggled wires and transmission shifted perfect and fluid is perfect. Opened up harnesses and found a can of worms. Ordered another speed sensor connector and will solder all the open wires to the coils as a wiring harness is not available. Shop would have put transmission in and not fixed it if she would approve if I had a guess.