I have a 99 ranger that we just put a new transmission in. When we first start driving it doesn't want to shift properly and you have to manually shift it. Once the O/D light starts flashing the transmission works just fine as you would expect it to.
I have searched many forums and always see posts about the transmission acting up when the O/D light flashes but have not found anything where it will NOT shift properly until it does.
I have pulled the codes and it says speed sensor A. This ranger only has the one speed sensor in the rear-end and does NOT have one in the tail shift.
I have replaced it twice just in case the first one was bad. But I still have the same issue.

Any ideas why my transmission does not shift until AFTER the O/D light flashes?

 

What is the actual code number ? should be P07xx
I believe speed sensor A is inside the transmission, and not the one in the rear-end that you replaced

 

I will have to re-pull the code here in a bit. But it is my understanding that the 4r44e transmission does not have a speed sensor on it and that the 99 ranger uses the speed sensor or abs sensor located in the Rear end..