Quick update!
I started this thread a few months ago after my own issues and now in winter (when it’s colder) I am seeing a lot more early 2010’s GX460s same issues reported.
Manual shift mode for the first 15 minutes on our rig has made it so there are zero issues.
After reading a gazillion more threads, posts, etc., I have come to agree it’s not just speed sensors, electrical connectors, etc. Likely a mix.
This is where I think there is more hope -
Diagnosing Solenoid Performance Faults in A761, AB60 & A960 6-Speed Transmissions - https://www.sonnax.com/tech_resources/345-diagnosing-solenoid-performance-faults-in-a761-ab60-a960-6-speed-transmissions. I have seen this posted by Acrad prior too.
The issue is I cannot find on a forum where someone did the zip kit and end plug fix and reported back. I have seen two folks on the Lexus 460 community mention it.
I think this summer I’ll work with a few reputable transmission shops to see who can test the valve body, transmission, etc., and has the know how for the Sonnax parts. If they can do that, I may as well do that, some solenoids, speed sensors and shift improvement kit (valve body). Hoping somewhere around $1700-2500.
IF that doesn’t do it for this common issue, it’s sport mode for life. I don’t want to dump another or original $8k for the same issue in another 90k.
I’ll report back if I run through with it and would love any updates if other have.
Cheers!