If you look at the diagram I sent you and read the description of the fault please it Says : Poor gear Shifting Quality, does not indicated any shift or lock up SL problem
1-The P0785 code is usually internal clutches damage or dirty filter
you can try changing fluid first
2- You can check these solenoids by checking resistance and know if they are defective Using an voltmeter set to resistance testing
3- If the solenoids are okay , then that means internal , clutches, TCC converter etc...
4- To take out the valve body and get to the solenoid it calls for 4.2 hr labor , now they dont list part number , but just by calling the dealr and give him the vin# ***** can get it for you since each solenoid has a seperate name ( S1 thru S5 shiftying solenoids) SLS SLT SLU
Solenoid SLT, SLS and SLU Measure the resistance between both the pins in the solenoid connector. Correct value: 5.0-5.6 ohms.
Solenoid S1 Measure the resistance between the pin in the solenoid connector and the transmission ground terminal. Correct value: 12-16 ohms. Solenoids S2-S5 Measure the resistance between the pin in the solenoid connector and the transmission ground terminal. Correct value: 11-15 ohms. If the resistance of any of solenoids S1-S5 is incorrect Replace the solenoid. See Replacing solenoids S1-S5.