New member here... over the past few days I have been reading multiple posts regarding harsh downshifting from 2nd to 1st, my vehicle is a 2006 GS 430 with 110,000. Km / 68 k miles, from what I gather, SIA Electronics is the place to resolve this issue, however, being from the Toronto area, I was hoping that someone may have found a local area shop that has performed the same repairs to their ECM with success... Anyone ???

 

Only the 2006 GS300 has ecu issues, plus your only at 110k km on a 2006, so im assuming this car sat a lot not driven. I think you might have a sticking solenoid. Have you tried changing out the transmission fluids? If not I would drop the pan and change the filter aswell. Also maybe spray some cleaner on the solenoid that is responsible for the downshift. A good transmission shop can do all this for you

 

Thanks for the info, it developed this problem just before I put it away for the winter last November, it has been driven on a somewhat regular basis to this point, and I actually have an appointment today to do the tranny fluid/filter, if he can’t spray the Solenoid, I will look into that as well... here’s hoping 🤞

 

Have you changed the trans fluid to this point? I have an 06 430 with 178k miles. I was told it’s lifetime fluid but ended up changing it at around 100k miles and again just last week. Not sure what the correct answer is but I’d be interested to know if changing the fluid hopefully solves your issue.

 

I actually changed it a couple of years ago just because, that was before I had this issue, and it made me think they might have not done a proper job, not a Lexus dealer, my appointment today is with a Lexus mechanic who has his own shop, so here’s hoping. With regards to this being an ‘06 GS300 problem only,

I found this earlier as well

 

Just installed my ECM after getting it back from SIA Electronics, car is running silky smooth, as it should. Went through he gears a bit...ok a lot, and its a relief to have her

back in order. Kudos to SIA

 

same here. fixed through SIA, yet it took them 2 weeks total, so i was without the car all this time.

now i mentioned that rear windows stopped responding to the buttons on drivers door. thats weird. could they mess something up?

 

Did you preform the window relearn? If not I would try that

 

uhm, no. didnt know thats a thing. thanks, ill try