LScowboyLS

yes, and as great as the 95-97 generation is, the 98-00 cars are a lot better!

if it is any consolation, all cars from the 1990's need new ECU caps, not just Lexus's - this is a big reason that many cars are now in the junkyard, they have this problem, and yet it was never correctly diagnosed, and the car wasn't worth further investigation at $100/hour

Yamae

The 98-00 cars have newer engine and newer circuits. Those new processors used in the newer ECU consume less current. This reduces the stress to those electrolytic capacitors compared with cars before. But Toyota has kept using the same series of capacitors of Nichicon PF(M) or PR(M) that containing "quaternaty ammonium salt" and as the car ages, there still exists a high possibility of the corrosion or leaking problems as is written at the page 568 of this pdf file prepared by the JST (Japan Science and Technology Agency of Japanese Government) .

It says,
The high basicity of the R4N/GBL system caused a serious corrosion problem that resulted in liquid leakage through the rubber seal. This leakage was caused by the cathodic reaction generating a concentrated alkaline substance around the cathode tab, which has a nobler potential than the cathode foil.

You will find that one of R4N/GBL is "quaternaty ammonium salt" reading other part of pages and I must add that a LS400 after 98 also has a time bomb. The time is somewhat longer than that of before 98 though due to the less stress.

LScowboyLS

what years did Nichicon PF(M) and PR(M) go out of production?

I recently opened up a 1999 GS300 ECU and there are no Nichicon capacitors, only Chemi-con & Matsushiita

Yamae

As far as I remember, they have been manufacturing those up to 1999. The end of the shipping was 2000 though.

cali108

iTrader: (1)

I have 80% of these symptoms on my SC would it be smart to say my ECU is bad?

I looked inside and its perfectly clean, didn't see any leaking capacitors'

I experienced the following simultaneous yet intermittent issues on my 1992 Sc400
except the red highlighted ones

● problems in getting into diagnostic mode or scanner says "no communication"
● random dropping into "limp home" mode
● OBD port is unresponsive, seems dead
● throwing random fault codes
● engine won't rev out/rev limits at 4000 or so rpm
● engine runs like crap,then suddenly runs fine again
● random not starting or cutting out
● low idle or erratic idle
● often very hard to start, requires starting fluid
● transmission will not automatically shift, only manual shift is possible
● no A/C compressor operation
● idle speed rolling up and down, or sometimes too low and sometimes too high
● speedometer not working reliably
● speed (cruise) control not working *never tested in limp mode
● tachometer not working sometimes
● air bag light flickering intermittently
● A/C going into reset with flashing front defog light
● check engine light on sometimes, but no codes stored, often in concert with ECT light
● ECU not communicating with scanners or not displaying codes with jumper installed
● bad sulfur exhaust smell in concert with not running right above






Any Advice would be helpful, or even better anyone have a ECU I can test before I purchase one?

dc893

I do see you are in FL as well, too bad the only spare ECU I have is another LS one or I would definitely let you use mine to test things out. It could be your ECU since I hear sometimes they don't always look bad.

Maybe somebody in the SC section could help you out testing things. I don't know where they are in an SC, but in an LS it is easy enough to remove.

LScowboyLS

Two things:

I would say that 92 SC400 is even more commonly affected by ECU capacitors than perhaps any other single year or model of Lexus, and one of the 47uf caps is a real bear to do on this one! - even for me! - it is underneath the casing frame, and a real patience tester!

You may be in luck, I will be vacationing in Destin later this month if you want me to take a look, you can also test the ripples with a multimeter as Yamae described earlier in this thread, to verify that this is the problem (more reliable of a test than visual) but since you have the most common year and Lexus model for this issue, I have not a doubt that this is the source of all or most all of the issues you are having on the list!

a junkyard or ebay ECU will not really do any good, as it needs new capacitors as well, and I have never opened a "rebuilt" one that had the correct caps installed and a nice job done, so cannot recommend that route either.

cali108

iTrader: (1)

sounds great! please stop by....

SC93

==================

Except for a few of the items listed above, I had the majority of these issues until I did the
cap replacement (10 new caps) job two weeks ago. Car now running like new and my latest
gas milage is 22.8 MPG in town with a/c on. Never been this good before.

My car is a 1993 sc400 and only has 90K miles but as cowboy says, almost an absolute given
that car of this age is due a rebuild.

My circuit board also looked pretty clean except for some micro leakage under a couple of the caps so general appearance can be deceiving.

LScowboyLS

This is all it takes to have many numbers of problems and very serious ones with how the car runs or shifts or A/C etc.

RA40

iTrader: (6)

Mine was equally same but noticing that slimy web just under the cap was the telltale sign of issues to come. Not having to clean up the mess makes the swap even smoother since the solder pad will be in good condition.

cali108

iTrader: (1)

I'm feeling better that this could definitely be my problem, especially the shifting and A/C issues.. now, I just need to test it or replace/repair I really wish I had a friend to swap ECU with, to test.

simrx3

anyone know how long these caps take to show up? mine still haven't showed up yet..

simrx3

just do the mod man.. cost is low and low hours to do it.. and you safe guard from any future issues even if it isnt the problem.. just sayin..

SC93

My caps from digi-key arrived 4 days after placing order. I live in Florida.