I was cornering decently hard today getting off the highway in my 06 LS430 and I got a vsc and check engine light coming out of the turn. I plugged in my obd2 scanner right away and got no codes or incomplete monitors. My first question is whether these car's codes typically require special readers or not, I also wonder if anybody else had experienced this 2 part problem and what may be the cause/solution.

Secondly, this car is having very rough downshifts in the lower gears. This seems like a common issue where the ecu needs to be fixed. I'm hoping this works, but I was wondering if anyone on here had experience/advice with that repair as well.

Thanks in advance for any help!

 

Welcome to the forum!

First off, how many miles on the car, what’s the maintenance history do you have any records of it? Have you done any recent trans service maintenance on it?

Do you drive aggressively? The obvious and easiest solution first is to do a drain n fill with fresh fluid and see if that helps cure the rough downshift, if it doesn’t, it could be a solenoid problem, but without any codes popping up, you’re in the dark in terms of what exactly is going on.

No these cars don’t need any special readers.

On my 05 LS 430 with a 158k miles, it needed a new transmission unfortunately as it failed internally pretty bad. I had a check engine light on including the VSC lite up, which the code was a solenoid failure. So I replaced the solenoid, replaced the filter and had fresh fluid put in, I even had the ECU repaired which I was hopeful in believing that was going to fix the problem, which it didn’t because I was still having shifting issues and the same code popping up.

long story short, I found a very low mileage used transmission for my car that I had installed for thousands of dollars less than what it would have cost to actually get mine rebuilt. The used transmission has been flawless, and I haven’t had any problems since.

Not trying to scare you, but it seems like these transmissions tend to have more problems than what people realize. I’m not sure what the exact reasons are, but it’s my guess, the lack of maintenance,
specifically replacing the trans filter and old fluid. And possibly because some owners drive these 430’s like sports cars, and wind up destroying the transmissions faster.

 

I'm sorry, but your post is incorrect. In the interest of future readers...
The Aisin (Toyota) A761E transmission is one of the most bulletproof/reliable transmissions ever produced.

 

Then why is it that so many members on this forum are having transmissions problems, mainly with the 04-06 MY?

I’m not saying that you’re completely wrong, but it seems like these A761E trans are failing or having issues way before 200k miles. I’m curious to know how many members here have the original trans that has over 250k miles.

The time that I had to replace my transmission, there were quite a few other members here that were also experiencing bad, or none existing shift points, CEL coming on, I actually remember someone that did replace 2 solenoid valves in his 04 LS 430 and fixed it, we had similar codes I believe.

I do believe it also heavily depends on prior ownership. If the transmission was ever well cared for and driven sanely. Maybe these transmissions can’t handle being abused (driven hard) all the time and expect to last forever. Some transmissions are more sensitive to fluid degradation, which is possible with the A761E’s.

 

Because of the ECU. I have seen it over and over. Using the car with a failing ECU will damage the transmission over time. So, about the transmission problems, as soon as you feel the hard downshifts, fix the ECU before the transmission follows.

 

Hi, FYI my Gen 3 GS430 will only link to a high quality OBD2 Reader.
Neither of my cheap units work (they are fine on Mitsi, Honda, Subaru, Kia). A Snapon unit works fine.
cheers Tony

 

just got my ECU back from SIA Electronics and it solved my harsh downshift issue. next im going to be flushing the trans and replacing the filter for peace of mind.

 

I agree getting the ECU inspected and repaired first as well to see if that helps cure the problem. In the meantime a flush or drain n fill is worth a shot.

 

'06 LS430 with 246,000miles - My shift issue was sometimes hard downshifts, combined with sometimes no downshifts at all unless coming to a complete stop. If I were rolling in to a round-about (for instance) or slowing down in traffic without stopping completely, then accelerating again, the trans would stay in a higher gear instead of downshifting.

Turned out to be three (of the five) shift solenoids had failed. My mechanic dropped the pan (first time it's been serviced in 19 years) to find ZERO metal shavings - only burnt trans fluid. He replaced the solenoids and did a complete fluid flush. GOOD AS NEW. Shifts like a dream again!

 

I just posted moments ago about my experience, but I can attest to this assertion. The quarter-million mile transmission on my '06 LS430 got serviced for the first time in 19 years just last week to replace 3 shift solenoids (and no, I am not proud of having gone that long without a trans fluid change). Upon dropping the pan, my mechanic discovered ZERO metal shavings - even on the magnet - only burnt fluid. Almost everything on the 3rd gen 430 is brilliantly engineered.

 

You were super lucky then especially at that mileage!! Because there’s been a lot of us lately having transmission issues with the 6 speed 04-06 models.

They are great transmissions, but I think it depends on how they were driven for all those years by previous owners. And if someone had a lead foot or not, also possibly living in mountainous terrain, and or a hilly city with steep inclines which accelerates wear and tear of an drivetrain.