Currently I have been having a transmission fluid pressure issue that gives a (on-board) diagnostic code of P1810. I changed the "Trans Pressure Switch", the "Park/Neutral safety switch", removed the "Return Cooler Line (lower trans line)" and cleaned the "Adapter", then re-applied the original applications. I also changed the "Exterior (in the pan) Filters", and leveled off the fluid. Further investigation lead me to the understanding that the "4T80E" transmission has a "Duel Internal Fluid Pumps, and an EPC Solenoid" that could be (either) the problem. They are located inside the "Side Cover" of the transmission, on the Driver's Side" of the vehicle. The proper drivetrain tilt is the best way for the DIY mechanic..... But totally doable. I'm going to do mine.