Originally Posted by sMEGMATRON

I have a 94 ls400 and shes in the position where she cranks n starts but dies right away. Wont even hold the idle for .5 seconds. After replacing a few things, like the ect, the car would jump back into safe mode within a week or 2. So today i pulled out my ecu/ecm and found the connection of these 2 caps not looking like the rest and was wondering if they need to be replaced?
Sorry about the terrible pics, my phone is the best camera i have. 😅

Originally Posted by sMEGMATRON

Thanks for the quick response! I had a feeling the ecm was going to be an issue for months now and already ordered a couple 50v caps from mouser. Should they be smaller than the originals? I still need to order the rest but i wanted to confirm this before i started ordering some more.


Also, i dont have enough experience with soldering to trust myself to do it but, would it be a good idea to wipe the area of the leak off the board?

Originally Posted by Yamae

I recommend to replace all of them otherwise you'd regret the first job. You definitely need to clean the area thoroughly since the QAS is already leaked out. I hope it's not damaging the internal layer yet. If damaged, there's no way to fix it.

Those QAS capacitors printed PF(M) or PR(M) are totally different from conventional electrolytic capacitors and when they are aged, the condensation of the liquid causes serious problems such as the increased ESR, decreased capacitance and the corrosion around not only at the surface but also in the internal layer and shows symptoms described at the post #1.

The increased ESR alone causes the car not to run well due to the high ripple level forcing the processor to confuse. Those who replaced capacitors before the leak occurred commonly say that the car runs far better or as new. That's why I recommend you to replace all those capacitors printed PF(M) and PR(M). Sooner the better.

Originally Posted by sMEGMATRON

Ok thanks a lot! I really appreciate your help. Im just going to order a refurbished one on ebay and might just keep this one i have now to work on my soldering skills so i dont by have to pay for a refurbished one everytime the ecu fails.

Originally Posted by GenericUse

I got the parts and work done on mine for a grand total of $120. Don't know how cheap it'll be for a refurbrished one but after you replace the caps I don't think they'll fail again.

Originally Posted by jaaa

why dont you just order the caps off the first post? Only took me a few minutes and around $10 if I remember right.

Originally Posted by Giorgio13

Hey guys,
im going to pull my ecu today or tomorrow to check the cap quantities i need for my 95 LS. Is there any precautions i should take when opening my ecu to count my caps? Do i need a anti-static wristband before i open it up? Or can i just pop it open and count so i can order the caps?

thanks a bunch

Originally Posted by sMEGMATRON

or just follow the instructions on post #1

Originally Posted by Yamae

Toyota has started to use Nichicon's electrolytic capacitors that containing “quaternary ammonium salt / compounds" in the late 80s and has kept using them for a bit more than a decade. The reason why they used those capacitors was simply because the internal impedance was low enough and showed good performance in removing noise and ripples at DC lines.

A little before that many electronics industries in Japan started to use similar capacitors that were for non automobile use and faced serious leaking problems in the early 90s. The details are written below but all in Japanese.
http://ednjapan.com/edn/articles/1208/01/news006.html

I don't have the time nor the ability to translate all the contents so I will just translate the title.
“80年代末期の“亡霊”に注意” or “Watch out for the “phantom” in the late 80s”
The “phantom” here means the electrolytic capacitor which contains infamous “quaternary ammonium salt / compounds". Judging from the title, it is dangerous to use this type of capacitor without taking any special precautionary countermeasures.

Most of the electronics companies in Japan stopped using this type of capacitor in the early 90s or mid 90s for fear of leaking problems. But many automobile industries kept using them because they needed good performance. Another reason was that they have been used in high reliability type-capacitors. Nichicon has been manufacturing special versions of this type for the automobile industries using specially coated lead wires with special sealing rubbers. One of my colleagues evaluated them and found the automobile type much better than those types designed for home appliances applications but the lifespan was not as long as those electrolytic capacitors that use regular liquids. Also the high reliability types were very expensive. I cannot show you the details of the evaluation results but what I can say is that the lifespan is longer than roughly 10 years or so but you cannot expect a lot if used for longer than that.

As I fix different ECUs as a volunteer, I came across many failed Nichicon's PF(M) type capacitors these days, some 12 years old, some 15 years old. What I can say now is that my colleague has done a good job evaluating the capacitors using an oven in the accelerated mode. In accordance with that and from my own actual experience, ECUs older than 12 years are ready to fail someday soon or later, that I can say with confidence.

Below is a failed capacitor used in a 97 Celsior. You can see how the leg has corroded and the part on the board where liquid has leaked out.

Attachment 430229

Those who want to replace Nichicon's type PF(M) capacitors to avoid future problems, be sure to use low ESR type capacitors. Never select capacitors just seeing the voltage and the capacitance. I recommend you to use Rubycon's type ZLH or Nippon Chemicon's type KZH. These do not contain infamous "quaternary ammonium compounds" but their ESR is low enough. You also have to pay good attentions against electric static discharge when doing the replacing job. A wrist strap is definitely needed to use. Without it you might damage the ECU.

Regarding capacitors Rubycon's type ZLH and Nippon Chemicon's type KZH, the availability in USA is not so good. LScowboyLS was kind enough to try to find capacitors that were OK to use and he listed up at the post #1. Those capacitors are good enough.

Originally Posted by Giorgio13

hi Yamae,

would i need the antistatic wristband to open the ecu to check cap quantities before i order? I have an electronics repair guy who is gonna perform the repairs on my ecu. I will provide him with the correct caps as you and LScowboy have suggested. Is it essential he use the same flux and rosin types LScowboy suggested(rosin core solder 63/37 (Radio Shack p/n 64-015 or equivalent)
rosin solder flux (Radio Shack p/n 64-022 or CAIG DeoxIT rosin flux p/n RSF-R80-2) in the first post? I want to set this guy up for success.

thanks for your input