Your Ls is hard-shifting on 2-1 and 3rd? No CEL codes or anything like that? no check engine light? Nada. And vehicle drive good other than when stopping shift hard.
Have 05 CL package. Had same problem. Took vehicle to Lexus and try quote me a Bad ECU for $1900+450 of service. So got my vehicle back and send my ECU to SIA Electronics In Tilden IL. They fix my ECU for $180. If u facing same problem your best luck to send your ECU. This transmission are bulletproof. I mean you still have to maintain it.

 

how hard is "hard"? Like banging / tires chirping or just something you can feel through the steering wheel?

 

Shifting should be if performing as designed so buttery smooth as to be almost unnoticeable. The only time I might feel a slightly abrupt shift would be occasionally when the car is cold and driving very slowly for the first shift or two. That would be my extent of nit picking with our proven transmissions.

 

You can feel in the steering wheel. Just if like you just slam the brakes. And yea I get you it should be shifting smoothly. So I notice allot people having same trouble. I’m guessing the capacitors in the ECU go bad.

 

Mine shifts semi-non-buttery only when going into 6th if it is not warmed up all the way. Other than that, I love the way the shifts are almost instantaneous and unnoticeable unless I am watching the tach.

 

Maybe I should send in my ecm into SIA Electronics. Mines been having some harsh shifting from 1-2-3 3-2-1 since I picked up the car earlier this year. So you guys are saying that the shifts should not be noticable in this transmission? I just thought it was normal, my 2003 es300 shifted the same as my ls430. I've only driven 2 automatic transmission cars in my life, the ES and the LS. I just assumed that these auto transmissions jerked and are general slush boxes.

 

I’ve heard the Es is the one with that problem. If it’s doing it recommend to send the ECU to SIA electronics. Like I mention dealership going want take your 2k. I work on a dealership my self and my foreman told me they have to do the TSB and recalls for free. And so you can go to Lexus.driver and pull up all the history of the vehicle but it had to be done on Lexus. So u can see if your vehicle has been recalled or any tsb has been done. I’ve checked my 430 and they wasn’t any history of recalls. This is for free just make an account.

 

I have read in older posts shifting problems with the 6 speed transmissions were from cracked solder joints in the ECU. If you're good with a soldering iron you may want to look the ecu over yourself before you send it off.

 

From Lexus

 

As a current ls430 owner who went through exact symptoms of harsh shifting, I may recommend to do couple of tests to see if it’s a transmission or ECU (whether MAIN or only transmission module) fault. By switching to 3 gear sequential gears, do you observe the reasonably similar harsh shifting or it does feel smoother?

 

for sure. My problem was proven by the dealership. I knew for a fact it wasn’t a transmission. Fluid was always good and it always shift perfect. They wanted to sell me a ecu for 2400 with labor. So I send out my ecu to SIA and give them a try. My calibration code was up to date.

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