Based on the code and your description, there is either an open circuit or short to ground in the line pressure control circuit. The line pressure solenoid valve controls the transaxle line pressure for smooth transaxle operation based on signals from the throttle position (TP) sensor and the vehicle speed sensor (VSS). If the shift is harsh, the pressure is likely too high.
If you look at the first two pics below, I provided the wiring schematic. It was a page long, but I had to cut it in half to make it readable for you. I did overlap them and highlighted the wires related to the solenoid and where they connect at the PCM.
The remaining pics are the diagnostics related to the code you provided. Take a look through them and let me know if you are comfortable doing them.
Let me know what you find or if you have other questions. Also, here is a link you may find helpful:
See pics below.
Images (Click to enlarge)
Tuesday, August 31st, 2021 AT 7:24 PM