Hi Christian .
Thank you for doing this test helps a lot ,
Okay first i want to do the basics as this could end up with an expensive repair so we don't want to leave out any simple issue that could cause this issue .
First make sure the fluid level is correct ,after a good drive should be on the highest level
and the fluid should be a transparent red to a light brown .
If the fluid is a dark brown to black then you have what i was thinking of an internal damage .
Good lets say the fluid is a light brown or red still.
The Code P0732 is Gear ratio error in 2nd gear .
Have the input and output sensors checked as this may cause this problem.
If all are good oil is clean and right level then your P1776 is the cause for this issue, and there is also a TSB for this issue .Please click here for further information
The solenoid switch valve is not in the solenoid pack it is in the valve body.
If replacing the valve body assembly for DTC P1776 Solenoid Switch Valve Latched in LR Position first inspect the build date on the solenoid pack. If the build date range falls in between 3001 and 0603 replace the solenoid pack not the valve body.
If you need further assistance with this transmission issue then please get back to me with the reply box below
If you accept my answer now i still can work with you after wards until we have this issue sorted out .