bought a 2006 hhr lt that would not up shift no problem replaced shift sensors and now it up shifts fine now when i put it in reverse or neutral it still goes forward the reverse lights come on ok but still it pulls forward was told its most likely a locked up drum but that all worked before i replaced shift sensors any hints on where to start

 

I would start with the linkage on the trans.

Do the back up lights come on?

 

X2 check the linkage

 

We’re you able to figure this out?

 

A 1 timer, never came back.