Having a problem I haven't found in any threads. Only code I get is p0720. I changed the sensor Speedo is working fine. Truck stays in 2 and 3. When I manually shift into 1 the wheels lock down. It won't shift into overdrive and it does not slip. From take off it is gut less. No other codes. Changed the filter as well. Fluid is clean. Any help or ideas?

 

Carefully check all wiring harnesses to make sure they aren't damaged or not plugged in all the way.

 

There are many sensors. Which one did you change?