Poor Shift Quality at Low Speeds on Lexus LS430

Problem Description and Possible Solution

Poor quality low speed transmission shifting may be noted. Our technicians tell us updated transmission software is available which may correct this concern.

Problem Data
RepairPal Verified
Average mileage: 122,323 (19,895–305,000)
5 model years affected: 2001, 2003, 2004, 2005, more2006
32 people reported this problem
Viewing 1 - 18 of 18 comments
When I am at a very slow speed and step on the gas the car revs to about 2000 rpm, hestiates and then jerk and then accelerates. It is very noticable at low speeds around 5 to 10 miles per hour. But from a dead stop it seems to shift fine. I had this problem for a while know it with the low low miles is a big disappointment. Suggestions before I get beat over the head for a new tranny from the dealer?
Down shifts too early and is very jerky when you come to stop. Brakes checked and ok, Transmission checked and all fluids, etc. good, new silnoid and no change, new battery, no change. All sensors did not indicate any problem. Was told at Toyota Dealership to get new transmission. Was told by excellent repairman that he thought problem was in wiring/computer. Don't want to spend $3,000. to $4500. on transmission if that isn't problem. Looking for suggestions on what to do and what could be problem.
If I want to take off from a standing start from a signal light to attempt to pass another vehicle my vehicle seems to buckle a few times and then works normally. what type of problem am I having?
As a Technician of Lexus for 5 years I too drive a 2005 LS430, in my career as a lexus technician i have never seen a LS or SC 430 transmission replaced nor have my co-workers. I Too had a Downshift Drivability conrshdithin where when the vehicle downshifted from 3rd into second it would be a little (harsh) but when it downshifted from 2nd into 1st it would be very hard almost stopping the car. i know every TISB for this car and there is one for a ECM re-flash for (Poor Shift Quality at Low Speeds) i first verified my ECM was fully up to date. Thinking It could ONLY be the transmission I installed a factory new transmission before even leaving the parking lot i noticed it was still there consistently on the 3rd to 2nd and even more noticeable on the 2nd to 1st downshift. knowing just how well tested the the factory transmissions come i knew the problem had to be the ECM. replaced the ECM and Fixed the Hard shifting. keep in mind there is no real way to diagnose the ECM is bad especially with no (codes) or anything to start from in most cases all you can do is have the transmission fluid checked (most likely very dirty because is a sealed transmission with World Standard Fluid) all you can do is gamble a $1500 ECM or a $3000 transmission. Next time i will put my money on the ECM cause these transmissions really are bullet proof.
Downshifts from 2 to 1st too early, causing engine braking. Tranny shop shaking their heads after replacing controller, dont want whole overhaul
I also have had poor shifting at slower speeds especially when going down a hill and idling. It is sometimes erratic. Lately it has been acting very strange by not shifting up when it should and spinning at high RPM. I thought it might be the transmission fluid but there was no improvement after getting it changed. I don't yet have a solution although I'm bringing it to the dealer to have them look at it. The battery was dying at the time (barely turning over when starting) and I wonder if it is somehow an electrical problem affecting a sensor although I would have expected the system to provide enough current while running with the alternator active.
I posted this problem a while back for my 2004 Lexus LS430. I took it to the dealer and they did a software upgrade. After that the problem was fixed but the car was idling very high we hot, around 1100 rpm. Bought it back a 2nd time and with an adjustment the hot idle speed is down to 600 to 700 rpm. Now it shifts correctly. I got it in before the 9 yr warranty problem for this issue. It was a known issue and they extended the warranty....Jogger
when the car downshifts 3-2 2-1 feels like im hitting the brakes car slows down abruptly i read somewhere that a person put a tranny in but actually was the ecm any thoughts
The transmission has always felt jerky at slow speeds. Lexus always told me this was normal. I finally found a TSB that addresses this problem. After all these years of Lexus telling me this was normal, I finally got Lexus to update the computer a few months ago. It works a bit better.