I have a 98 Automatic. The tranny will not shift into overdrive unless I lock the torque converter, and most recently even then it was not that willing to go into overdrive. I have heard a bad tps sensor could be my problem. Will a bad TPS throw a code?

 

Check your battery terminals first. Dirty battery terminals have wreaked havock on tranny's, but once you clen em up they shift fine again. My tranny is living proof that it works.

 

Your locking the tc how? That toggle switch deal?