I agree. SIA was closed during a portion of the holiday and has a bit of a backlog. They are quoting 10 to 12 day turnaround times until they can work through the backlog.

 

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Trust me. Don't use SIA. Use the link I sent you previously

 

I trust you and took your advice. I sent my ECU to a company in suburban Dallas earlier this week. I'm waiting for him to diagnose and repair if possible. Turnaround time is important to me so I just called SIA for information. They might do a perfectly good job but their reviews are mixed so I went elsewhere. Thanks.

 

It isnt an issue using someone else provided they are reputable. Good luck.

 

relentless motorsports ? I've heard they know how to fix this issue as well

 

I doubt you ll get results from this. Other solenoids are suspects in your case.

 

Maybe, we'll see. What other solenoids are you referring to?

 

You don't fully trust me haha but I understand.. It's a public forum. I hope the guy in Dallas fixes it for you. The link I sent you is not a Dallas company, but again, there's multiple companies that can do the same thing. All I know is the ebay link I sent you is the cheapest, fixed what SIA couldn't, and is the fastest turnaround. The guy is very responsive versus other bigger companies.

Good luck!

 

So far, so good.

The rebuilt ECU was delivered a few hours ago and I quickly reinstalled. The car now shifts smoothly and the hard downshifts are gone. The smoothness of the transmission has improved overall as a result of the ecu rebuild.

The work was done by Relentless Motor Sports (https://www.relentlessmotorsportstx.com) in suburban Dallas. He was knowledgable, responsive and offered a very quick turnaround time with personal attention. He was a little more expensive than the other providers discussed on this forum but he was well worth it. I would highly recommend this company.

I appreciate the comments and suggestions, thank you.

 

Nice! Hopefully this effect lasts long time. Do you mind to provide an update a month later?

 

Perfect. Glad it worked out. At least you have new fluids and some solenoids. Hopefully the right fluid was used.

 

Glad the ECU was the problem. What was the cost of the repair?

 

The definitive thread on the topic. Update if you get a chance:
https://www.clublexus.com/forums/ls-...nsmission.html

 

I also begin to have hard downshifting with my 2004 LX 430. I only feel it when the car is less than 10-15 mph. I tried my code reader twice and got no code. "Bovineplan" said he got code P0756. I took the car to the dealer, and they also got no code either. The service manager said the mechanics performed a pressure check on the transmission and found the pressure was low but not enough to trigger a fault code. I see "LX430Lexus" said he is getting replacement solenoids. I see Rock Auto's website shows 3 different solenoids for the car. Which solenoid, all 3? Where are these solenoids located? Are they accessible without removing the tranny? I sent ECM Guru an email regarding the price and turnaround time for the ECU. I will wait and see what the cost is. I will also try and drive the car in Sport Shift Mode and see if the problem goes away. I was surprised to find a service bulletin by Lexus acknowledging the hard shifting, but they only applied it to the GX model. A LX430 and a GX430 is very much the same. Anyway, here you go if you are interested. I hope I got the link correct. SB-10061736-2273.pdf (nhtsa.gov)

 

I recently bought an '05 LS430 with the hard downshifting problem and sent my ECM out to SIA electronics. It came back after about two weeks. The hard downshifting is definitely improved but still noticeable. The technician wrote a note stating that although they fixed the transmission electronics, I still would benefit from a software update. I assume this is referring to the "ECM Calibration: Shifting Enhancement" for '04-'05 LS430's.

How can I know if my car would benefit from this enhancement? I called a local Lexus mechanic and they said that this update only applies to 2004 models and they wouldn't like to try it on an '05. But on TSB TC006-04 I notice that it gives "production change" VIN number as JTHBN36F*5005700". How do we read off our own VIN from this? If the number is larger, does that mean that we do not need the update? Starting at the asterisk in the production change VIN, my VIN is "X5017..." does this mean that the update would not apply to my car?