Transmission hard downshift from 2nd to 1st gear feels like getting rear ended
05-09-19, 10:26 PM
#31
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Join Date: May 2019
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Same problem
I had. My ECU fix too. But mi car does the same hard downshift. After a driving it for a while. Don’t know what the problem is.
05-10-19, 02:39 PM
#32
Are you guys checking your driveline u joints to see if there is any play? Lift the car up and yank on the driveline and gently pry to see if theres any play. If there is I would replace them as that can cause a hardshift.
If that doesnt help, try draining the fluid and use amsoil atf fluid
If that doesnt help, try draining the fluid and use amsoil atf fluid
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Russjz (06-14-24)
09-17-19, 04:43 PM
#33
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ECU or ECM???
The instructions below 👇🏾👇🏾👇🏾👇🏾 are on how to remove the ECM but multiple times it’s referred as the ECU are the y the same or did I just screw up and removed me ecu ??
So after some more research, i have concluded that the ECM (located under the hood) is the one that will have to be sent in for repair not the ECU (located at passenger side). I will update everyone on the end result for the members and others if they happen to come across this problem. I will overnight the ECM for repair tomorrow on monday and notify my results. The ECM will not need to be reprogrammed its PNP. The repair will consist of fixing bad capacitors and what not. I am almost certain that this is the issue, after countless research therefore, i will be going with this route. WISH ME LUCK EVERYONE! Here are some links that i found was helpful. A member, GEEYES300, had the same issue and he had sent his ECM in for repair with success.
HOW TO REMOVE ECM
https://www.clublexus.com/forums/is-...moval-diy.html
HELPFUL LINKS
https://www.cargurus.com/Cars/Discus...16018_ds771423
https://static.nhtsa.gov/odi/tsbs/20...61736-2273.pdf
https://www.clublexus.com/forums/gs-...0756-code.html
LINK FOR REPAIR
https://www.ebay.com/itm/Lexus-GS300...9ZJFbe&vxp=mtr
HOW TO REMOVE ECM
https://www.clublexus.com/forums/is-...moval-diy.html
HELPFUL LINKS
https://www.cargurus.com/Cars/Discus...16018_ds771423
https://static.nhtsa.gov/odi/tsbs/20...61736-2273.pdf
https://www.clublexus.com/forums/gs-...0756-code.html
LINK FOR REPAIR
https://www.ebay.com/itm/Lexus-GS300...9ZJFbe&vxp=mtr
07-10-20, 09:13 AM
#34
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Location: WI
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ECM Location
Thank you
02-17-22, 10:47 AM
#35
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Ecu repair for hard down shiffting on lexus
I have a 2007 Lexus IS 250 with hard down shifting when coming to a stop. The transmission oil was changed and it was incredibly dirty and surprise the car continued to do the same thing. The shop told me it needed a new transmission. It just did not seem correct because the car only did the hard down shift when coming to a stop. So after reading the threads on this site I saw that the ECU was the problem and everyone talked about SIA Electronics doing a great job and fixing the problem. So I removed the ECU and sent it to SIA Electronics in Tilden IL and they repaired the transmission circuitry within the ECU.
Had it back in one week and it cost me $180 and we plugged it back in (no programming needed) and IT WORKED!!! It runs smooth like a new car and even my gas mileage improved. So if you are having the same problem why not try this first it will cost you less then a new ECU at the dealer or even worse getting a new transmission and finding out it did not work.
Thank you everyone for sharing your story and helping me out with my 07 Lexus.
Had it back in one week and it cost me $180 and we plugged it back in (no programming needed) and IT WORKED!!! It runs smooth like a new car and even my gas mileage improved. So if you are having the same problem why not try this first it will cost you less then a new ECU at the dealer or even worse getting a new transmission and finding out it did not work.
Thank you everyone for sharing your story and helping me out with my 07 Lexus.
02-21-24, 10:32 PM
#36
1st Gear
Join Date: Feb 2024
Location: Ca.
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Hello all, just would like to update CL. My car is fixed! sent my ecm in to get repaired, and wow it is alot better than i had thought! I noticed my car drove smoother than before. There is no harsh downshift and my up shifts going from 3rd to 4th is a lot smoother compared to before. I do not know if there is a correlation due to the fix, however, i do notice a difference in performance. SIA have saved me thousands of dollars. I hope this post will help others if they happen to come across this issue.
04-12-24, 10:17 PM
#37
ECU programming is not needed unless a new or a "donated" unit is installed. SIA will send back the same exact ECU you sent in, so no programming is needed.
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