I wish someone with a Mines ECM would let Cowboy or Yamae examine it. We need a good look at that daughterboard or whatever is in there.

I ordered enough caps from digi-key to do 3 ecu's. The total was $33 (including $20 for 2nd day shipping). Glad to hear this job will make it run like new. I bet many people just give up and junk the car after throwing a ton of cash at a 20 year old car. My mechanic said the lack of power was baffeling to him because he replaced and checked everything that could make the engine lose power. I almost junked the car also. Makes you wonder how many lexus cars are in the junkyard because of this issue. Hope this does the trick and the bad caps did not ruin the board.

the bad caps did not ruin the board, but they may have damaged it - after you remove the old caps and clean the leakage area with vinegar and a toothbrush, take a magnifying glass look at the little copper circuit board traces that were affected and make sure they have not been eaten in two, or that will need to be addressed.

the traces will be discolored, but hopefully not severed by the caustic old electrolyte

If your mechanic doesn't realize that an ECU issue can cause a major loss in power or a car to run terrible, then it's time he went back to changing plugs on a 1971 Ford pickup - something he is qualified on :egads:

The capacitor's application depends on the circuit they are in. Capacitors do lots of different things. Switching creates high ripple current. That ridiculously overpriced $1200.00 switch located in the power steering rack-- that circuit puts a lot of strain on the capacitor in that circuit and that ripple current is created by switching, the capacitor is not filtering anything; rather it is releasing energy at a certain point to trip a switch. But yes, a high ripple current cap is going to be fine.
In a direct current filtering circuit, e.g., after a half or full wave bridge rectifier, the capacitor's purpose is to filter or smooth out the voltage, but that is not what is going on here in these ECUs. Or in a circuit to a speaker coil, there the capacitor's job is to prevent DC voltage from being applied to the speaker's coil. Direct current applied to a speaker coil will cause it to overheat. And that exact same capacitor in another circuit will help create DC voltage, by smoothing out the voltage sine wave (if viewing on an oscilloscope).

Then, could you tell us what is going on there in those ECUs?

yamae - you are not just incredibly smart, but also a wisecracking smart-a$$ - I love it!

I hope you have a beautiful single daughter, because you would be the ultimate dream father-in-law! :D

I'll subscribe to this thread now. :thumbup:

can someone tell me which capacitors I need to order for my 1995 LS400 please. Im ready to take a crack at it

From LS CB's post:

Qty. 2 of 10uF - 50v
Qty. 1 of 47uF - 63v
Qty. 2 of 100uF - 10v
Qty. 1 of 220uF - 25v

CAUTION!!

Even the best 4 companies (Rubycon, Panasonic, Chemicon, and Nichicon) can have a run of a bad series of capacitors, even nowadays!

The following series manufactured 2003 -2010 have high failure rates:

Nichicon HM and HN series
Chemicon KZG and KZJ series


the following series is not inherently bad, but I would call it weak, will not deal well with excessive heat or ripple or power issues caused by other caps or components failing around it:

Rubycon MBZ and MCZ series


it may seem like I am singling out Japanese capacitors for my biitching, but it is a sign of my great respect for them that these 4 leading Japanese brands are the only ones I will use from any country!

please stick with recommended brands and series!

to remove the ECU - remove bottom pretty light panel under glove compartment at passenger foot area, then remove lower glove compartment (it can be a bit tricky due to a hidden bolt or two located within secret panels within lower glove compartment.)

once lower glove box is out, then disconnect negative battery cable, unplug 4 connectors to ECU - then remove ECU (a book size aluminum box among several others, but the only one with 4 connectors containing a total of 100 wires going to them)

if you need to drive the car while waiting on parts or before you get started, there is no need to reinstall the lower glove compartment before operating the car, just secure ECU and replug the 4 connectors

Attachment 498614

Are these also for JDM celsior's?

Look at posts 146,148,151 for my problems.

Update on my 93 LS. I got the caps shipped, and got into replacing them. I could tell after removing the two that had leaks that the circuit board was toast. the section of the board with the leaking caps was damaged into the middle layer. The electrolyte is very corrosive and if left too long, will do incredible damage to the circuit board.

Even so, I tried to replace those caps. After installing in the car, it blew the 20A EFI fuse!!

But all is good now!! Found an ECU on eBay for $150 and when it came and i installed it, all my problems were solved. I will still replace all the ecu caps when i get a chance. Thanks for all your info. Another LS saved from the scrap yard!!

Word of caution to others. If the board appears severely damaged, do not try to fix it. Just replace the ecu with a known good one, (and it is highly recommended to replace all the caps if you have the time). I was lucky the fuse blew instead of damaging other critical system components. Good luck to other and i hope this helps.

yes, but make sure you use the group listed for your particular year

the smart way is to inventory which caps you actually have inside your ECU, and then order them, you can drive the car while you wait a couple of days for them to arrive, just reinstall ECU in a couple of minutes and leave out lower glove compartment.

please use the caps linked to in the first post of this thread