propcop

2005 LS430
145600 Miles

All of a sudden the transmission wont shift into 6th gear no matter how fast I go.

Also the 3 to 4 shift takes additional RPM'S to complete the shift when the temperature drops below 60 degrees f. Once it makes the 3 to 4 shift one time it shifts in a normal fashion until the car cools down, usually overnight.

Not leaking fluids of any type.

Ant thoughts what I might be up against?

Thanks in advance

rkw77080

Are you getting any DTCs? For example P0710, P0712, or P0713?

propcop

No codes, car runs and drives like a Lexus except for the above transmission issues, I still drive it every day. its my daily driver.
Thanks

rkw77080

The symptoms you described (difficulty shifting from 3rd-to-4th, and 5th-to-6th) seems to suggest that the engine coolant temperature (ECT) sensor is the culprit. According to the repair manual, ECT failure "could" cause a DTC to be recorded.



Troubleshooting without a DTC will be a bit more challenging.

propcop

Thanks RKW
I'll look around for one this week and replace it. Certainly hope its not the ECM as the documentation suggests it could be.

Thank you again!

05ls430518

iTrader: (1)

Rkw saves the day again Lexus member of the year for 2017 he has my vote.

rkw77080

Thank you for the compliments, 05ls430518... Happy New Year, everyone!

Again, it's difficult to troubleshoot without a DTC. According to the behavior you described, it's also possible that the ECM has placed the transmission in Fail-Safe mode (designed to prevent further damage caused by a certain failures). That was the reason why I asked if you are getting DTC P0710, P0712, or P0713, suspecting that the ATF temperature sensor was at fault. Lexus parts are expensive and I don't want to send you down the wrong path to waste your time and money.

propcop

Thanks for the updated information, hopefully a fix is insight.
I know where the water temperature sensor is located but no idea where the transmission temperature sensor is located, could you tell me where it is located?
Is there a convenient way to look up the part numbers for each of the two sensors on this site?
Also, is there a better way to purchase Lexus parts on line rather than from a Lexus dealer?

Again thank you very much for your comments!

Bob

rkw77080

Bob, please take a look at HERE for details on engine coolant temperature sensor installation, and HERE for some suggestions on sources for OEM parts.

Please refer to the sketches below for ATF temperature sensor replacement...

propcop

Again thank you for the updated valuable information. I'll try the coolant sensor myself but it looks like the ATF sensor is a dealer or independent garage job.

Thanks again, great information. No where but here could this information be found!

Bob

Walker34

I was seeing this same problem with my 2006 IS350 w/181k miles. It just wouldn't shift into 6th no matter what I tried. I was seeing no error codes.

After reading this message, I ordered a new ECT from Amazon, Toyota part #89422-33030.

Let me say this right now: Replacing this one innocuous part was pain. The ECT was in the very lower back of the engine, facing the battery. I had to remove the battery and use a combination of a video borescope and a teenage son's skinny arms to be able to find and reach it. (I would also recommend a 3/4" stubby wrench to remove it, as there is almost no room to maneuver in there.)

However, the scraped knuckles paid off! Two SOLID hours later, we had the new ECT installed and the car is now shifting into 6th perfectly. This work and a $46 part saved what was going to be at least a $500 service at the local Lexus dealership.

Thank you very much, rkw77080.

weldthedif

This is what forums are all about!

RelentLex

Don't mean to revive an old thread but any chance you'd know the part# for oem ATF temp sensor? Having troubles finding it. Thank you