Took truck to dealer to have them check line pressure(adapter was $200+ they checked it for free) they told me line pressure is perfect and in perfect correlation with the line pressure sensor. They noted that the clutch apply flow(amount of fluid, not pressure) was in flawless spec on all pistons according to the transmission pressure switches PID data - meaning my internal seals are not leaking and my clutch pack clearances are correct. I believe I am looking for a short in the transmission wiring harness, and or a damaged #2 check ball, as this is all I've found in common between P0876 and P0731. Has nobody else had this issue before?

 

Finally found time to post my solution to the problem. Ultimately ended up rebuilding the valve body to include all new check *****, accumulator seals, and a very thorough cleaning, as there were a lot of metal filings. Truck shifts amazing coming off that 5.5k limiter without slipping or going into limp-in mode now. I was heavily advised (against my own training and experience), not to take this valvebody apart when rebuilding the transmission, by a senior tech with 25+ years of experience. That was the wrong call. This valvebody is ridiculously simple to disassemble, clean, and rebuild. I do recommend trying this for the P0876, after all other bases have been covered(filters, harness, CGI's, fluid level/condition) the majority of the causes of this code stem from the solenoid pack or fluid issues, so do make sure to check everything.

 

Congrats. Good work. Thanks for posting your fix.

 

Must not have been a transmission tech, gotta clean everything on a rebuild. Thanks for getting back with the fix details.