GX460 transmission, no reverse

[Keywestelec]

The other day, I went to back my 2010 GX460 onto some ramps so that I could easily air up the spare tire. While attempting to back up the ramps, my transmission made a squealing noise and then I lost reverse. Drives and shifts perfectly up and down through all forward gears. Hooked up a scanner and saw an inactive (archived) P2714 code and nothing else.

I dropped the pan this morning to check fluid condition and to see if there was anything obvious. Fluid was somewhat dark, but definitely not burnt. Pan was very clean with no metal, no clutch material, or anything else I noticed. Put a new filter in and filled it back up with new fluid, plus some Lubegard.

Transmission still shifts perfectly up and down through all forward gears. Will now shift into reverse and idle backwards, but revving the engine causes no change in vehicle speed. Has no power to back over any obstacle. No new codes.

I'm of the opinion that the transmission itself is probably okay and my issue is likely in the valve body or the solenoids. It feels to me like pressure is bypassing in reverse. But I haven't had much luck finding information online that could help me further diagnose the issue.

I'm guessing someone here might have some information to share that will help.

 

[iwashmycar]

There seem to be a lot of threads like this out there, but havent come across a real definitive answer.

I DID see, a comment based on a LS400 trans that the O-rings on the little shift solenoids 'flatten out' and this may let them not hold pressure....Just figured Id mention that since, you said it feels a bit like "pressure is bypassing".