2003 CLK 500 code P0778
 

2003 clk 500 keeps getting code P0778 "pressure control solenoid B electrical" I've changed the conductor plate twice, changed the solenoid, changed the valve body, even changed the wiring harness. What else could cause that code?

It may be a bad solenoid int he valve body. It might also just have trash in it. I'd remove the solenoids and thoroughly clean them. Also, remove the horizontal plates on the side of the valve body and inspect the return spring under there to make sure none are broken.