Chosen Solution
Shifts through the gears just fine, but when you let off the accelerator and it downshifts it makes a loud noise and the rear wheels tries to lockup. Sounds like gears grinding. Jacked up the back of the truck, and the axles spin free as can be. Only does it on downshifting.
@wlw7241970 ,William, Check the transmission fluid level and condition, if low fill to correct level. If fluid is dark or smell burnt, change the fluid and filter and try. Have checked for any diagnostic codes that could lead to the fault. I believe it is usaully associated with the hydraulics and there are a few areas to look at possible loose/broke TV cable, the servo unit (a hydraulically applied piston) could be sticking, bad accumulator, pressure control solenoid, check balls sticking,dirty valve body, etc,etc.. You can check some of the stuff out your self, a lot should be checked out by a good tranny technician, I believe they just have to pull the pan to check. Some of the auto parts suppliers offer free code reading like Pepboys, Nappa, Advanced auto parts,etc and some of the guys are very knowledgeable and may have seen the issue often and put you on the right track. Good luck. I hope this helped you out, if so let me know by pressing the helpful button.
