[QUOTE=robbyboy32;10464885]I was experiencing the rough shifting in my 2006 as well. I bought 9 quarts of Toyota WS, a new oem transmission filter, oem pan gasket, and replaced the solenoid involved in the rough downshift. The solenoid that fixed my problem happened to be the SLU(lock up solenoid). These 6 speed transmissions seem to have solenoids go bad, but after diagnosing and changing my car shifts perfectly now at 240,000 miles. I had dealt with the crappy shifts for about 7 months before taking this on myself. I did about 4 hours searching for parts, possible problems, ECU resets, and diagnostics for solenoid voltages. Once you drop the pan they are easy to remove and test. 3 of the 9 quarts I used doing a simple drain and fill, which did not fix the

 

There are many threads on this topic in the forum, but I still think this one is the authority with the best and most specific results. Thanks to everyone who has contributed!

Ideally I would like to start another thread for an official directory of places to get the chip fix done. There can't be just one. For those of us with one car and SIA says 10-day turnaround right now, that is a $600+ rental tab added to the bill, and of course shipping. @Kodawari found that place in Reseda, CA (LA area) that did it. I live in Salt Lake City now and am trying to do a little research but not having luck. It would be great to get a directory going of confirmed places around the country. Confirmed, not "I think they probably would..." or "they do stuff like this". @BigBoomer confirmed in a different thread that soldering is not for everyone, and there is knowledge and skill to it; it isn't just 'me use flame, me melt metal'.

 

My code was ECT P0761 Solenoid C Stuck OFF which popped up on heavy foot. Symptoms include problematic down shift and sluggish response on acceleration. I changed Solenoid S3 but the problem still persists. On the dilemma between transmission change or ECU 🤔. All suggestions are highly appreciated 🙏

 

I have experienced several P0761 or solenoid related code problems at different shops and replacing the solenoid did not always effective. The clogged pressure line often causes the problem. Some were fixed just changing the ATF 3-4 times. Another one needed to remove the solenoid and needed to clean the pressure line.

These made me to try to check the solenoid first without dropping the pan and I just apply the DC10V (not 12V) to the solenoid and confirm that clicking sound can be heard. When the sound level is good enough, I just replace the ATF and drive the car for a while and then replace the ATF again. Repeating this mostly fixes the problem. One bad example was needed to drop the pan and replace the strainer though.

 

The car developed noticeable shifting from 1 to 2nd gear, with a slight punch forward, as well as slight shaking at 40-45 mph speed.

ECU was fixed by SIA, I do not suspect it might be at fault.

Will look into doing full service on the transmission fluid replacement + new filter, gaskets, clamps, bolts, cooling hoses, Original WS fluid + at this time I will purchase new SR 3-way, SLU, SLT solenoids.

I will update if this becomes a solution.

 

I changed my transmission and Voila my Lexie floats like a dream. My codes disappeared and my Lexie shifts super . My issue s solved but when the Mech removed the exhaust and after refitting I think there s a slight leak which lead me to another code P0420 and B2799. Gotta fix ‘em now.

 

Having just had a Toyota dealer perform the old Toyota Service Bulletin on the transmission, which is a software flash, I ADVISE anyone considering more expensive or time-consuming fixes to GET THIS DONE FIRST. It is low hanging fruit, usually 1 hour of labor at the dealer and I kid you not, I think it cured me. My 430 is new-car smooth now. Perhaps it will revert, but I will cross that bridge when I come to it. Right now I'm thrilled. I had it done last Wednesday and was traveling so I have had both highway and in-town driving to test it on, going on 5 days now. Very happy!

 

Thanks for sharing this.

I was not aware that Lexus allows the ECU flash with an update to the 2006 models. Are you sure it wasn’t the 2001-2004 model software fix?

 

Good point. Thanks for calling that out. Mine is a 2004 (beyond the recall though) and I think I do recall the date range cuts off in the early-built 05 models.

 

Please do keep us give an update in a couple of weeks. I always wonder if this is a battery reset effect that returns after some time.

 

Battery reset is definitely a temporary solution, it always returns to pre-reset condition after few weeks of driving.

From my experience, dealerships incorrectly state that Battery reset and Adaptive memory reset in the transmission are the same and caused by unplugging the battery for few minutes.

However, whenever they perform software flash or Techstream “Reset memory”, it definitely clears the memory for the transmission to relearn the shifting and driving pattern. So, I would say the effect will last “permanently”.

 

4-week update: It was 4 weeks ago today I had the TSB done. It is doing great. Yes, it has relearned a little bit, but I still say 80% improvement and well worth it. I think it even made the idle smoother?? Maybe it can't have any effect, but for now I am pleased. Now I think I will take some others' advice and pursue a full transmission fluid service, even though supposedly you are not supposed to have to.

 

Australian 2005 LS 430 at 300,000km suddenly developed same issue. Harsh Downshift from 2nd to 1st pulling up at the lights. Took it to Lexus and wasn't showing any fault codes on the reader, and transmission fluid had been drained and filled a few years back. Lexus advised they had seen this before and ECM/ECU needed replacement part 89661-50820. Brand new US$3000 but no longer being made. Australian model, so needed to source second-hand Australian ECM, which wasn't possible, none of the wreckers had any. Found a company in Melbourne, IMGroup, which offered an ECM repair through code ECMLGSREP for about US$700. Same repair as on GS300/430. Sent it away, 2 weeks later, came back and problem fixed. Amazing, as you would have thought it was a problem with the transmission.

While I was still driving the car trying to research the fix, I was advised by a mechanic to put the car into neutral when slowing down at the lights, this worked very well to avoid the hard downshift. I was told if the harsh downshifting continued, I would wear out the clutch and could be up for a new transmission. He said many people keep driving the car for months and then the transmission goes into limp home mode and that's big bucks. So the take away is: coast to a stop in neutral while you figure out your repair plan.

 

As a temp solution, nuetral decel helps, yes. Glad the ECU fix worked.