I had posted a thread a few months ago regarding my 2006 SC430 (79,645 miles). When I slow down, the car is thrown into 1st gear (causing me whiplash half the time). I can tell that it doesn't shift right when reaching 40mph. There's like a delay. I took it to the dealer and they said it was either the engine computer or the transmission. They gave me a price of $3000 (ECU) or $7000 (transmission). I got some great advice from some of the posters here, thank you for steering me in the right direction.

I ended up taking it to a local transmission shop. It sat there for over a month. They said the same thing, ecu or transmission. No help whatsoever. I ended up with a dead battery that I had to replace. If you have a trusted mechanic, be very thankful!

I decided to replace the ECU myself. I found one online to match my computer number exactly. I contacted a locksmith for all the re-programming. This morning he came and did what he had to do. Total cost $357 (part and labor). I couldn't wait for him to leave to test the car out. I drove it around the subdivision and to my surprise my problem was solved....so I thought.

I was all excited driving to work. And then it happened. I was approaching a red light and boom....jolted and thrown into 1st gear.

So, at this point, I'm thinking that I never made it out of 2nd gear when riding around the subdivision. I made it into at least 4th gear on the way to work. Any thoughts? I was going to try replacing the solenoid next. I've gotten a price of $700. But will still call around.

I called the dealer for the heck of it and talked to one of the guys from service. He was quite nice and said the odds of it being the transmission was slim. He looked it up and said that since 2013, they had 5 transmissions replaced.

As a reach, I'm going to disconnect my battery for 10 minutes and say a quick prayer. I'm not optimistic though.

Thank you in advance!

 

 

 

 

If disconnecting your battery was unsuccessful, I believe you may be on the right track going after the solenoid. I once had a transmission rebuilt on another vehicle with an aftermarket solenoid and about a year after the rebuild it began to make harsh shifting adjustments similar to what you have described. My only advice is that if you do replace the solenoid go with OEM and not an aftermarket solenoid.

 

Have you checked your motor mounts? As silly as it sounds, MANY people report serious transmission problems, only to find out it was their motor mounts.

Here is just one example: https://www.clublexus.com/forums/sc4...problem-2.html

 

 

Good thoughts. It's always best to begin with the least expensive repair and work your up to more costly repairs if necessary.

 

I would say ecu. LS430 & 06+ GS has this problem. I seen some on the LS page send their ecu out to SIA electronics to get rebuilt.

 

As you mentioned in your other post you had a shift solenoid code. Its time to follow the proper repair steps and you might find the solenoid needs to be replaced.
They do get dirty. As the trans wear the particles stick to the magnets in the solenoids and BANG they can't work