TrapMaster

Did some more diagnostics stuff today on mine with the help of a friend who is far more knowledgeable on this subject than me. We found both of those resistors to be good but the 2 of my replacement caps (a 220uf and 10uf) appear to be bad as well as one of the smd caps (C110). Any ideas as to what would cause the 2 new capacitors to fail? My guess is the smd was collateral damage from the old 220uf leaking. I can order all the components but I think at this point a good remanufactured ECU or a quality professional repair is probably in order.

GenericUse

Okay, this is getting insane. I've just gone over my original ECU - the one that came with the car - which was repaired with the proper caps from the first page. I see no indication of any damage to the board, and all caps appear to be firmly attached with no solder leaking onto other traces. I then compared it to my ebay "rebuilt" ECU, and all of the capacitors are in the correct spots (the quotation marks are because it was never actually rebuilt, so at least I can use it as a reference). And yet, with the original ECU, even after the repairs, the car would stall out past 20% throttle, the last time I tested it. My newX2 ECU is having the same problems as the first new ECU, with random loss of power, strange shift patterns, and now, randomly losing ignition for seemingly no reason.

I've got the pinouts for the ECU, so tomorrow I'll be backprobing the original and the newX2 ECUs in hopes of an answer. None of this is adding up.

GenericUse

Opened up the NewX2 ECU. They just stuck random capacitors in there that're roughly the same physical size as the originals. Yeah, they apparently think that computers run on capacitors that are the same physical size, uF and voltage be damned. Luckily it seems the board wasn't damaged in this "repair" so I'm ordering a triple set of capacitors in case some are bad. The original ECU has magically stopped having several of its problems, including spark knock. Still cuts out under load though. Think I'm going with the second ECU for now - it has plenty of problems, but at least I know it'll get me there.

Edit - looks like the only 10uF, low-ESR cap available in the US right now is this one, so I'll have to go with that. Oh well. Hopefully they work.

MichaelPm

What about on a 1996 Es 300 I have all these issue ran fine then runs terrible wont communicate with obd then works fine i replaced alt battery fuel filter .mechanic couldnt find issue then it did it,then it ran fine again.Now its stuck in a lot.

jsulliva

I fixed my mom's 1991 LS400 ECM a few years ago by replacing the caps as instructed here, for which she is very grateful.
I bought the car new for her in 1991 and she still loves it. Probably under 40K miles.
She spent a lot at Lexus and other mechanics trying to get it fixed before I found this post.
I don't have the numbers off it anymore - sorry - but the cap list did not exactly match mom's ECM.
IIRC I had one cap left over.

Mom is in Calif. Sister in Calif (lives with mom) purchased for her a junkyard ECM and wants me to replace the caps in it as a spare.
Junkyard yellow paint says 1993 LS400.
Paper tags "1UZ-FE" (that's the V-8 engine IIRC). Bar code sticker 175000-4110J and 12V. Another sticker 0-467.
Connectors / Pins 26P-16P-22P-26P.
Toyota P/N is 89661-50032.
Capacitors (all on lower board in ECM except as noted):
Q2 of 10 uf - 50V C102,C110
Q2 of 15 uf - 35V C715, C716 (upper ECM board)
Q3 of 47 uf - 63V C809, C824, C828
Q1 of 100 uf - 10V C106
Q1 if 220 uf - 10V C108 (reading post, some boards have a 220uf-16V cap)

I am hoping that the ECM number and specific capacitor listing will be helpful, as I imagine the caps vary by ECM / Toyota part number (not surprising to me).

A) The Toyota ECM part number listing near beginning of this thread implies 89661-50032 should work in 1991 LS400, but can someone confirm that, please?
B) It also mentions that if swapping ECM, there may be problems like "no start" because of the security system.
So how does one get around that, please?
Or has that proved to not be a problem after all?

Thank you.
John

Yamae

I don't know much about the ES300 since those are not sold in Japan. Does your ECU has electrolytic capacitors printed Nichicon PR(M) or PF(M)? If so, you definitely need to replace them.

Yamae

There was a big design change in August 1992 adding rear O2 sensors, changing cold injection system + evap system and some oters. Unfortunately an ECU for a 93 can't be used for a 91.

RA40

iTrader: (6)

Was this the Windom? The chassis coding XV_ _

jsulliva

Thank you but there must be more to this.
It sounds as if the changes you described might lead to a different wiring connector and pin configuration.
I am questioning this because the part number chart in post #1 shows the ECM 89661-50032 was produced 09/1990-08/1992 which would cover 1991 model year.
Perhaps there is something about which model the changes were targeted to, e.g. California emissions or something?
Which would apply to my Mom's 1991 LS400 made for the Cali market.
Maybe the junkyard man wrongly identified it as 1993 when it is in fact 1991 or 1992?

Yamae

The ECU 89661-50032 is for an LS400 model year 92. It has some differences but it would work for a 91. As long as your mother's car is a federal and w/o traction control, the possibility is high. As far as I know, differences are mostly related to improvements or minor corrections. For the better confirmation, I would ask the junkyard man, "Are you sure this is from a 93?".

Yamae

Thanks Mike for the information. So far, I have never heard of any Windoms's ECU failures. I should say that Windoms were not sold well here in Japan and I only knew just one around me.

jsulliva

I will inquire about the ECM.
Thank you for your advice.

GenericUse

Alright, properly rebuilt and working ECU in the car. Made no difference. Thinking it's a ground, would be nice if I could actually see the two passenger side engine grounds.

N0b0dy

Just did my 1995 Celsior.
ECU Part # 89661-50241
The ECU has 9 Capacitors as follows:
C101 10uf 50v
C102 10uf 50v
C120 100uf 10v
C121 100uf 10v
C141 220uf 16v
C781 47uf 63v
C831 47uf 63v
C804 15uf 35v
C805 15uf 35v

Yamae

Thanks for the report.
Incidentally don't you have this problem in the video?