DTC 520319-1 is "Speed Sensor Input Function: Output Speed: Data Valid But Below Normal Operational Range - Most Severe" and can be caused by: bad battery, blown fuse, bad ground circuit, low power, bad sensor circuit. Most likely issue is a bad wire in a connector or a connector has come loose over time.
Finally figured it out. After replacing all transmission sensors and transmission harness and attempting to calibrate several times, I checked all sensors on the display and found out that the new TOS sensor was faulty ??
If you can access the Calibration menu within the display, fo ro Calibration, search for Calibrate XMSN valve and calibrate it.
Follow instructions on the screen and be sure to floor the gas pedal once calibration begins.
Let me know....
no code found with this dtc #