Yamae

There are 4 speed sensors. I mean all 4 tires are checked the rotation by each speed sensor for the ABS and (the traction control). ( ) means some model does not have this function.

xaper

Some updates to my issue.
I checked the speed sensors and they are ok (according to the manual I found). I then realized that it was my fault the code showed up, as I reved the car with no gear, so naturally the sensor was getting wrong data. Anyway, I am sure the sensors are ok, so it leaves me with the mechanical issue most likely. Since I lost much time and I really want my car back I went to the toyota/lexus and asked them to fix it. Yet they didn't want to as they told me they have no experience with it and would not like to do the transmission, which leaves me with two options, 3 actually:
- let the guys from automatic transmission repair shop fiddle with the car and pray they can fix it, however in the other place they told me it would cost around half the price I bought the car (+ for the same amount I can buy another ls400 with working transmission and put it into mine and have it for spare parts)
- leave it alone and buy a new one, however I really like this one (or any other ls4xx) so I am not sure it is wise to buy another one cheap and have similar or even more problems
- take out the transmission and try to fix it myself (I have some mechanical experience and have someone to help with much more experience, maybe not transmission, but hey, mechanics is mechanics)

LScowboyLS

This is the worst option, Aisin transmission don't tend to fail and they have no clue what to do here, you will spend $2000 and it still won't be right or even any better


another transmission might be an option, if you can't get this one going


Another very bad plan. - Automatic transmissions are different animal, this is only a good plan if your buddy has extensive transmission experience - there is a reason typical mechanic won't go near an automagic transmission


how many miles (or kilometers) on this transmission?
what country are you in?

I suggest at this point you:

● change transmission fluid and filter with genuine Toyota T-IV and a genuine Toyota filter

● go through all of the troubleshooting steps in the factory service manual?

xaper

My transmission has around 250k kilometers. I live in Poland, Europe.
I have already changed the transmission fluid (according to lexls.com tutorial) and used 13 litres to get the same bright red colour outgoing from the hoses as the incoming one (maybe that much was not required but since I bought it anyway I just put everything I had). It was Toyota T-IV bought at the dealer.

I guess I will try the troubleshooting first, but is it possible to do it without the Toyota/Lexus tester. I don't have the OBD II, so my only option is the lexls.com system with putting the wires inside the OBD I.

LScowboyLS

you do not need a tester to do 90% of the troubleshooting tests - you may need an electrical multimeter though.

surprised that your LS400 does not have OBD-II as the LS400 in USA did have OBD-II in 1995

you need to double check the transmission fluid level (which I realize seems obvious, but you would be surprised things that can happen)

did you say you replaced the filter? - if so, was the replacement filter the real Toyota part?

xaper

After reading the forum I was also surprised not to find OBDII.

No, I didn't replace the filter (is it replaceable or you just clean it, because if it should just be cleaned then I did it).

As for the fluid level, I am a bit confused and yes many different things happen. As I described before, the first time I "fixed" the transmission was just unscrew the transmission pan, clean the filter and add 2 litres of fresh fluid and the car was fine until I engaged the PWR mode and use it for real. So this time first thing I checked was transmission fluid, however for me the dipstick is really not very informative (the COLD level especially).

And I was really happy when I once again unscrew the transmission pan and it was only around 1 litre of oil coming out, as it meant to me (knowing the previous) I just need to add some more and it would be ok (despite the level on the dipstick), but the next day I was yet another time disappointed as it fixed nothing.

LScowboyLS

are you certain it is the correct and original dipstick?

the COLD level is just to get you in the ballpark, while you are filling it at home - once you have gone out and gotten the transmission fully hot (about 20 minutes of driving), then check hot on a VERY LEVEL surface - the HOT setting on the stick is a much more accurate measurement than COLD

again, don't want to insult your intelligence, but not sure what you know and don't know, and better to hurt you ego and yet fix the car if it is something silly, such as, you realize the car must be running in Park while you are checking the fluid level with the dipstick, right? (and you should have just shifted through all of the gears a couple of times slowly, including reverse.)

xaper

Well, I am not 100% sure, but it looks like the original one. The problem with my HOT level is that I can't get the reading, as the car is not moving, so I have to rely on the COLD one.

Don't worry about my getting insulted, as I really want to get the car moving and even the silliest idea might be reasonable, as I might have skipped it. But in this case I already knew it.

What is really strange, is that it should not be the case of wrong oil level, as just before the final drive I checked the HOT level after driving more than 1 hour and it was absolutely fine, but still I wish it was the oil level - this could be a real relief to me and my wallet I suspect.

LScowboyLS

the transmission in your car (Aisin A341E) is perhaps the most reliable transmission ever put into any car, it is common for these transmissions to go 500,000 km with no issues - so it is unlikely to be an internal problem with the transmission, unless the previous owner did something really dumb that you don't know about (like not coming to a complete stop before shifting from reverse into drive, wrong fluid, etc.)

I would proceed with the troubleshooting steps in the service manual! - and also pull the codes with your older connector and a jumper wire, as shown on lexls

xaper

Well, you can never be sure, but I think it was not the previous owner but me. As described in my first post in this thread I changed the radiator and drove (1 km or so and not really fast) the car without the right level of fluid inside (which came off during the change). However since then I managed to fix the transmission by adding the right oil and cleaning the filter. Inside the pan there was no sign of a worn metal parts, so I stopped being suspicious + the car was running even smoother than before.
And now I am having the same exact problems, so I feel it died because of me, but anyway I will do the troubleshooting procedure and write here about the effects so that anyone else knows what to do in such a case.

LScowboyLS

the good news is, most of the time people ever have any problems with this transmission, it is not the internals, it is things like neutral safety switch, ECU, speed sensor, etc.

this is a good thing!

LScowboyLS

the reason I said to change the filter screen using a real Toyota screen is that previous owner may have used an aftermarket filter and these have a habit of falling into the pan and then car will not go!

xaper

Well I still believe it will be something not internal as you describe. And by the way, do you mean the ECU which I changed the capacitors in, or is there another ECU for transmission, as I have read once there is another ECU for transmission but couldn't check it with any other source.

LScowboyLS

no, the main ECU is the one for the transmission

here is a test you can do, especially if you have access to a lift, as the connector is a bit hard to get to:

there is a very large main electrical connector going into the transmission, it has a LOT of wires (far more than any other connector on the transmission - that is the ECU to transmission connector - correctly unplug it by pressing the release tab - do not force it (I know it is a tight squeeze and you may have to remove a brace or something that might be in the way)

now the ECU is out of the picture, car will not automatically shift, but you should be able to shift into any gear and drive the car, by shifting into each gear, as if it were a manual transmission!

PS - always disconnect the negative battery cable when disconnecting any electrical connectors!

fsuguy

Hi,

For what it's worth, I had been having similar problems with my '92. The car started having problems going into reverse - forward gears were fine, it would take some time to get into reverse. Sometimes I had to let it idle for 10 to 15 minutes before reverse would engage. Finally, forward gears began to fail. The dealership wanted to simply put in a rebuilt/new tranny. I asked them who they used for rebuilding and took the car to those guys. They looked inside the tranny and said that the clutches and hardware were fine, but the rubber seals were all too hardened to effectively seal the passages. Basically, they resealed the tranny using OE seals, etc., charged me for the rebuild ($$$) and problem was resolved. Of course they did not change the shifter solenoids, so the problem returned later. But that was fixed by changing the solenoids.

Now, I am not sure how difficult or challenging it would be to change out the seals, but I am sure someone on here who have more experience can weigh in on that. From what I have read, the UCF10 engine and A341E is a pretty robust engine-transmission combo, and it would have to be really, really mistreated to give you problems.

HTH