Yamae

It is just easy to fix. When you start your engine, you wait about 20 seconds at the position of "ON" until the "trac-light" turns off. Don't twist to the "start" position for the first time when you start the engine after the job was done removing the battery terminal. This must be written somewhere under the dash in US models too.

Anyway congratulations on your success to fix the ECU, luxou812. About a year ago, I began to write about the capacitor problems here at Club Lexus LS400 replying to some people here who were having unusual and strange problems. But many here did not fully understood me.

Then there came up LScowboyLS who understood me well enough and he succeeded to fix his ECU. He decided to inform it to others. That was the beginning of the thread. He is kind enough to write the detail from the way how to remove the ECU to actual capacitors. His instruction is now helping people next to next.

LScowboyLS

I wish I had read yamae's capacitor posts! - It would have saved me months or years of frustration, by jogging my bad memory! - unfortunately I never saw his capacitor-related posts, but I did see some ECU theory posts that he published on CL, and that got me once again thinking about ECU operation and how many things that I was having issues with were ultimately controlled by the ECU, and it took me back to 15 years earlier and jogged my memory that I had had nearly the identical breakthrough working on old Japanese engines from the late 80's, when I had some issues with some old Toyota 1G engines, some early Nissan 300ZX VG engines and many early Mitsubishi DSM ECU's (Starion, Eclipse, 3000GT) with this same failing capacitor issue which I had my friend Todd in the Mitsubishi DSM club write up and photograph - here is my old post from 1998 which amazingly still exists on the Internet. Sometimes I wonder if this has not been a lifelong hobby in a strange way, as I first starting replacing capacitors in 1981 while living in Hawaii although these capacitors were replaced not due to failure but for audiophile purist reasons on vacuum tube (valve) based amplifiers (which by the way, are still the best in the world for recorded or live music) It's amazing how things in life just repeat over in cycles!

we are very lucky to have yamae here on Club Lexus as our expert ECU technical consultant, his ECU and engineering knowledge dwarfs all of the rest of us combined!

he has molded my knowledge on the subject of capacitor failure and taught me many key concepts, such as the fact that a low-ESR capacitor can have too low of an ESR and that finished lead length is very important and well as many other critical technical points

I have always suspected this, and always let the new capacitors "get to know" the other components in the ECU by putting the key to RUN position for 1 minute before initial starting after ECU repair, but I will now go and add this to the instructions in post #1

BobSmith00

Well I got the ECU out with little problem, other than the contortion act.

Visually all 6 capacitors look totally fine. No leaks or anything.

Could they still be the failure point even if they look normal?
Photos of them a bit later today.

LScowboyLS

YES! - at the early stage of this problem, there is nothing visible!

That is what made it so hard to discover this problem in the first place, I had to force myself to go back and reexamine the ECU a couple months later, after tearing my hair out trying to find the source of the intermittent problems, and what is crazy is, that between the first time I looked and the second time (maybe 2 months) the board had gone from perfect to almost completely ruined by the leakage!

have you found an expert at soldering?

make sure you triple check the polarity of the installed capacitors and their values after you are finished, it is very easy to put one in backwards or the wrong one in the wrong place!

it is also easy to get a clipped piece of a capacitor lead left on the board or a stray fleck of solder, keep reinspecting your work and also use gobs of flux on everything!

I mentioned that the caps can be bad and look fine in one of the very first sentences of post #1 of this thread, the main info post - read it a few more times!

BobSmith00

I mostly was asking just to assure myself.

I got a guy that used to do work on arcade machines that is willing to do the solder work. Planning to head to Radio Shack today to pick up a few things and maybe morrow get things done.

I also noticed this sticker on the side of my ECU


For some reason I expected other stickers (or at least one that looked different) on the case, mostly from looking at ebay and the like.

Brodi

LS, I can't believe how long you have been talking about this and last night was the first time I saw it. I just ordered twice the amount of caps I need to do the job on my 97 LS400 and now wish I had ordered a sack full of each size for all the year models. I have a few friends that have issues and am not doubting for a second that they as I all have the same problem ( CAPS ) LOL. For the longest I was missing on cylinders 1, 3, 5 & 7 and couldn't put my finger on anything that could do that. At one time I was sure that the oil control valve was the problem yet upon looking I could not find them on the 97 model with 4 speed auto. Lexus says the 97 LS with 5 speed auto engine has the but not my model. 1998 and on carried these little jewels and between them and screen plug-age could indeed to cause the single bank miss from incorrect timing. Anyway now i am missing on cyls 3,4,5 & 6 and after opening up my ECU VIOLIA ! There are those pesky little CAPs with one of them showing leakage. I will update after the new ones arrive and are installed but I am as excited as a pig in the mud & sun with high hopes that this is going to be the ticket to my problem. Thanks in advance and till then..........

LScowboyLS

that's a scary thought, but could be a good plan

well I see that the problem happened before for someone, I wish you could send good resolution pics of the re-manufactured ECU so I can see if they replaced the boards and what caps they used

one thing that is cool is that you have the latest and greatest firmware update (software) indicated by 50304 suffix

LScowboyLS

I hope you used the links I provided because the exact types are a very rare type of premium special Japanese capacitor

BobSmith00

I can see about snapping a number of high res photos on the morrow.

luxou812

After 3 days: Running exceptionally well. The car is back to old self. Sounds great. Full of power. Really impressive cold starts. Couldn't be more pleased.

I have appointment Monday with my mechanic who disconnected the a/c compressor about two weeks ago thinking it had failed -- the engine was reving intermittently and he said it was compensating for the attempted operation of the failed a/c compressor. I am hoping that this was instead an ecu issue, and the a/c will work when connected. I'll report back.

***

Huge thank you to LScowboyLS and Yamae. This thread is indispensable. I was too sick about what was happening to even call my mechanic again -- came to this site and found this thread. What a blessing.

You both have done a great service.

ありがとうございます。

Thank you!

BobSmith00

I've taken a whole mess of photos of the inside of the 50304 ECU.
First I'll put up the less than full res photos and if anyone wants larger they can tell me which one and I'll get those up.
A)
B)
C)
D)
E)
F)

LScowboyLS

weird, must have been reman-ed long ago, because it still has the problem capacitors

Candysking

Yamae & LS Cowboy:
Follow up to my post 2 weeks ago. Capacitor replacement clearly was my engine misfire problem. Running like a Dream 900 miles later.
I am still getting my error code for catalytic converter on passenger side. Keeps erring after about 50 miles of reset. Have not had the opportunity to put on open road for more than 10 miles at a time at 70-80 mph. Will probably have to replace.

Still having issue with tranny. Shifting at all gears is quick and smooth, even when cold, upshifts and downshifts. I think problem centers around torque converter, prematurely locks up during first 10 minutes of starting up cold, and when gradually decelerating, stays locked all the way to nearly braking to complete stop. It will finally release when engine is dragged down to about 300-400 rpm.

Once car is driven at various speeds for about 15 minutes, torque converter behaves normally, along with continued excellent upshift/downshift pattern.

I will need to have it serviced, but looking for advice how to steer my repair shop from getting into too aggressive service. Can we try intermittent steps to diagnose/repair? Partial drain flush, shift solenoid, or something else? What actually controls the torque converter lock up/disengage? mechanical, vacuum, ecu?

Twista4004

I had a few questions:

What difference is noticed in that last firmware update?

If there is anything desirable, is there a way to get it on an earlier ecu?


Also, Does anyone have any photos of the ECU LOCATION prior to removal?

I went to the junk yard and found a disturbingly mint looking UCF10. I then began to pillage and ravage looking for the ECU. I pulled plastic clips, pulled trim, pulled carpet and got to a box marked ABS. I would have pulled the whole seat for more clearance but there was no power to move seat to expose bolts. I then proceeded to yank this-n-that from the kick area on the right side. I looked at where the door harness went to but was completely unable to locate the ECU. I did learn how to remove the AC filter which was really cool (and disgustingly filthy. Makes me wonder what mine looks like).

Now, I'm almost sure I was staring DIRECTLY at the dang thing but was too daft to realize it but I just did not see anything that looks like the silver box other than a much-too-small-to-be-the-right-one box labeled ABS. I spent two and a half hours ruining this car for no grand gain. I feel quite unmanly for it, especially seeing as there were only 4 LS400s in the whole 1000+ car yard. All others of which were already completely bare.

Help. Please.

LScowboyLS

I suspect that the ECU is the first thing pulled at a junkyard, 5 minutes after it arrives at the junkyard. - try the office and ask for an ECU.

the are plenty of photos and diagrams throughout this thread showing ECU location and how to remove it and what it looks like, you need to read the entire thread, starting with the very first and main post, which has an extensive diagram of location and removal

by the way, a junkyard ECU is normally no help to you, it needs caps too!

it's only helpful in the case of caps that have leaked so bad in yours that the main circuit boards are damaged catastrophically