Krisplus4

I bought a 04 low mileage TL for the wife but it had numerous electrical issues from melted harnesses, she ran and drive great with no issues at all besides interior electrical and exterior lights not working. I decided to buy a 2008 complete parts car to change out all the harnesses, complete interior, nav and all the other 08 options. Took me 4 days and the car is together and everything works like it should except the issues with the transmission. The motor and transmission harness is the only 2004 harness that’s still in the car. A couple days ago she started up and ran great, when I put it in reverse she shaked and died and the D started to flash green. I started with the neutral safety switch and added a wire to take care of the flashing D light, but she still wants to die when i put it in reverse. Now I’m thinking it’s a solenoid or pressure switch that might be wired differently from the 04 to 08. I do have the motor and transmission from the 08 but it has higher miles. Looking for recommendations

thank you