DTC P0715: Input/Turbine Speed Sensor Circuit Fault: Description
WARNING: This page is about a different car, the 2002 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.
Input/turbine speed sensor signal is 600 RPM or less while engine speed is 1,500 RPM or greater and vehicle speed is 24.8 MPH or greater in "D", "3", or "2" range.