andys57

My '04 LS 430 has started having hard downshifts as I am coming to a stop. 3-2 is noticeable (about 10mph) and 2-1 is like an anchor has been dropped. Code reader shows a stuck solenoid (sorry, don't have code).

Independent shop I have used pulled the code and did a fluid change on the tranny to no avail. They don't' repair transmissions, only replace them. He suggested taking to a tranny shop and they might be able to isolate further and replace what's causing the problem.. Here we go with parts changing until they find out what's wrong, maybe including replacing the transmission.

Thinking it might be related to one of the service bulletins referenced on this website, called the local dealer. To my surprise, the shop foreman called me back and left a voicemail. He said it had been their experience that on the 04-05-06's this was an ECM issue, that people would replace transmissions that were ok only to find the problem wasn't the tranny and then had to replace the ECM. He said the tranny update would not fix this problem

Feel like I'm between a rock and a hard place as to whether to take it to the dealer or tranny shop.

Anybody else been down this path??

Thanks!!

toddmorr

i've had a random downshifting problems too, and after reading several threads here it seems it can be addressed by either a new ECM or tranny software update, depending on exactly what the problem is. A software update is around $150. Curious as to what a new ECM would cost, anybody know?

you also mentioned a stuck solenoid. That seems plausible and if so, why not just replace the solenoid, that can't be a terribly costly repair.....might well work OK.

YODAONE

How about replacing 14 year old transmission fluid and transmission "filter"??

Not recommending a pressure flush either but changing should be possible through disconnecting transmission cooler line hoses from bottom of radiator and filling a bucket with fluid, starting engine and drawing fluid, while second empty bucket catches old fluid.

For those less inclined, A transmission shop is likely likely to have a system in place.

05ls430518

iTrader: (1)

It is probably the shift solenoid it's gonna be $60-$150 I do not know I have not replaced one on a Lexus it's a simple thing to do though, have you tried taking your negative battery terminal off and letting it sit for 30 mins then bolt it back up?

k7q

iTrader: (37)

There's a TSB for that problem. TC 006-04. Bring it to the dealers and they reflash the ECU.

05ls430518

iTrader: (1)

He said he is throwing a code for a stuck solenoid as well as the dealer said that it's for 04-06 not 01-03 the op has a 01-03 from what I gather.

k7q

iTrader: (37)

Op has an 04. Says it in the first post line?

05ls430518

iTrader: (1)

On my bad he does I was assuming cause he said he had an independent shop do a refill of the tranny fluid and the Lexus dealership told him the ecm update wouldn't fix his issue sorry man I was not paying attention.

Super sorry has been a long day.

tallcaguy

A good first step is deal w/ the stuck solenoid. Reflash is the next. Changing the trans fluid is complicated in the 04-06's. I had mine changed 2x (w/in 1,000 miles). The indy did the first. Put in the same amount of ATF that he took out. Had the dealer do it the second time. Measure temp, etc, etc. Found that trans was 1/2 qt low. Every mechanic I've talked to says do not do a flush w/ an old transmission. With the reflash and 2 drain and fills, my 04 now shifts almost invisibly. Good luck