I'm having an issue with the 6r80 in my 2012 F150. 4-6 gears slip and also have really high line pressure, like over 300psi sometimes. 1-3 gears act behave normally and have expected line pressure. Fluid is also really high, high enough that every time i pull the dip stick it leaks more out of the fill hole.

Open to ideas.

Thanks,

Anthony

 

Did you try the simple things first like replacing the tranny filter, verifying correct fluid capacity within trans, checking for blocked lines/cooler. What's the history and mileage? Did this just happen overnight after 50k miles of smooth operation?