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All my crazy Lexus issues SOLVED!! (ECU-leaking capacitor)

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Old 10-08-12, 08:51 PM   #46
Kanderson1
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Default 1995 ls400 power problems

Hello forum...i purchased a 1995 ls400 for $2000. I noticed that the check engine light and all the lights on that side doesn't light up when i start the car. Also my power lags very badly....engine is noisy when it starts. When i drive, i have to press the accelerator to the floor to get it moving. I want to bring this car back to life! I owned a 92 ls400 a few years back...and it was excellent!! This one is such a disappointment, however i would like to know where to start to get it right.
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Old 10-08-12, 10:21 PM   #47
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I would start with this thread and replace your ECU caps to likely solve the power issue, and possibly also the caps in the dash cluster circuit board as well (basically the same job as ECU caps) since you said there are lights not coming on in it.

also bring the car to autozone or advance or o'reilly and get a free OBD-II scan - post the codes here

also would highly recommend you replace caps, rotors, plugs, wires, inspect timing belt, clean MAF sensor, clean throttle body, and fix PS leaks.

Last edited by LScowboyLS; 10-13-12 at 08:13 PM..
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Old 10-09-12, 06:10 AM   #48
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also make sure your throttle cables are in good shape
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Old 10-11-12, 02:00 AM   #49
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Also it just started jerking. I lost my gas cap, but im not sure if that affects it, although that did happen with my wife's S500. Suggestions??
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Old 10-11-12, 02:50 AM   #50
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Quote:
I lost my gas cap, but im not sure if that affects it, although that did happen with my wife's S500. Suggestions??
the gas cap is important on these cars, they don't seem to run right without it, and get the real Lexus cap - I would pick this up from the Lexus dealership TODAY - it is that important.

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Old 10-11-12, 08:19 AM   #51
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i noticed when fillin up that theres alot of suction no matter how empty the tank is
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Old 10-11-12, 01:32 PM   #52
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Quote:
i noticed when fillin up that theres alot of suction no matter how empty the tank is
your charcoal canister system maybe be clogged up as well
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Old 10-11-12, 01:54 PM   #53
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This guy sounds a little too smart to be hanging out with the rest of us


Quote:
Originally Posted by LScowboyLS View Post
to recall, I was the one with the 1996 LS400 with the following simultaneous yet intermittent issues:

engine running bad
very hard to start sometimes, requires starting fluid
transmission will not automatically shift, only manual shift is possible
no A/C compressor operation
speedometer not working
speed (cruise) control not working
tachometer not working sometimes
air bag light flickering intermittently
A/C going into reset with flashing front defog light
check engine light on, but no codes stored
ECM not communicating with scanners


well with no engine diagnostic codes to work with, I checked all of the grounds, voltages and other obvious causes, and then in a MacGyver-Steve Jobs moment of insight, I decided it must be the electrolytic capacitors inside the ECM, which had appeared fine in an earlier inspection a few months ago.

sure enough, upon re-inspection, 2 or 3 were leaking, I replaced all 6 electrolytic capacitors ,and now every single problem listed above is gone! - and the engine also seems to have much more power than it had even before the symptoms above appeared!

I now believe any LS400 over 12 years old would greatly benefit from having ALL six or so electrolytic capacitors in the ECM replaced with high quality new ones! - these were not part of a defective batch, but rather a quaternary ammonium salt capacitor issue, as explained by world-renowned ECM engineer yamae in post #8 below. (we are very lucky to have him here at Club Lexus!)

this is NOT something a junkyard computer would solve, it is an age and sitting up problem, a junkyard ECM would have the same issues.

the power difference alone makes it worth doing, and just because an electrolytic capacitor looks good, doesn't mean it is - if you have a 2000 or older Lexus, I HIGHLY recommend you do this!

PS - a new ECM would also solve the problem, those cost $2400 at the dealership, the parts I used to make mine just like a new one were $16 total to my door from ebay -
make sure you use 105C rated low ESR caps from reputable Japanese brands such as Rubycon, Nippon Chemicon, Panasonic & Nichicon

it is CRITICAL that the replacement caps be low ESR type and from one of the brands listed above - don't cheap out on your vital ECM!


~~~ special thanks to Yamae ~~~, who got me thinking in the right direction on this! (and also thanks to TV character MacGyver, it's what he would have done!)

no one understands Toyota ECM operation and design on Club Lexus anywhere in the same league with Yamae!

just consider him a guest expert engineer from Nippon Denso, and you wouldn't be far off.
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Old 10-11-12, 02:57 PM   #54
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Quote:
Originally Posted by LScowboyLS View Post
so here is the consolidated caps list for 90-94

Qty. 2 of 10μF-50v
Qty. 2 of 15μF-35v
Qty. 1 of 47μF-63v
Qty. 2 of 100μF-10v
Qty. 1 of 220μF-16v
Thank you very much! I plan to do this on weekend. As you suggest I will do the ECU 1st and then do the dash.

Regarding your comments on resistors - can you give a little more info on why no resistors have been replaced (Yanmae jump in) , when some do luck suspect to visual inspection as other poster suggests!

In the specs it does not say if it is LOW ESR or not, any thoughts on these NTE branded capacitors?
Click the image to open in full size.
220uf-16v

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Old 10-11-12, 03:56 PM   #55
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Quote:
Regarding your comments on resistors - can you give a little more info on why no resistors have been replaced (Yanmae jump in) , when some do luck suspect to visual inspection as other poster suggests!
it is rare to see any bad resistors on a Lexus ECU - perhaps yamae would know better than I - I have seen a couple of the light blue ones burned in half though

Quote:
In the specs it does not say if it is LOW ESR or not, any thoughts on these NTE branded capacitors?
I would shy away from off-brand cheap Chinese capacitors for your expensive Lexus ECU that costs $2400 new - yamae only recommended the premium Japanese brands of Rubycon, Nippon Chemicon, Panasonic and Nichicon for a reason!


Click the image to open in full size.Click the image to open in full size.Click the image to open in full size.Click the image to open in full size.Click the image to open in full size.Click the image to open in full size.Click the image to open in full size.Click the image to open in full size.

And if a capacitor is not specifically intended to be a LOW ESR type, then it isn't, and would be incorrect to use for this repair - and it also needs to be 105C temp rated, and equal or greater voltage spec.

Last edited by LScowboyLS; 07-20-13 at 02:41 AM..
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Old 10-12-12, 06:57 AM   #56
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Originally Posted by LScowboyLS View Post


ALSO - keep in mind that the capacitors do not have to be visibly leaking to be bad, therefore you want to replace ALL of them, even if they look fine!
good topic, i am not the person to solder my ECU so i opended it up just to see if there where any burn marks or capicitators that were out of specs.
Everything looked good so i closed it up.
Now you guys make me crazy telling me that i have to do the swap anyway all of them.
So i am going to ask somebody specialized in this **** to do it for me.



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aloha aloha i get a hard on from printplates ....

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Old 10-12-12, 08:24 AM   #57
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it would be great to know your year model and what those 9 cap's values are!
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Old 10-12-12, 08:42 AM   #58
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LexterLS40 what are your year, symptoms that you think its the ecu? I didnt notice mine had a problem it isnt actually on the capacitor yet but if you look on the road next to C104 is where mine shows leakage you may have to just get a high LED light and comb to see if theres visable damage already.

Click the image to open in full size.

Im not totally sure if this is something just laying there or its a scratch on lexters picture next to T802
Click the image to open in full size.
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Old 10-12-12, 08:49 AM   #59
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yes - 53bel - that leaking capacitor's caustic leakage is burning off those traces next to C104, that is why they are all dull looking compared to how they are an inch lower in the pic, if you don't get that cleaned with vinegar and new caps installed soon, you will have to fix the traces too - and that is very difficult!
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Old 10-12-12, 09:48 AM   #60
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thanks kind sir. and waiting on the last few to come in got most of them now ordered bags/boxes of 5 and 10's just incase plus for the dash and future to help others in need.
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Old 10-12-12, 09:48 AM
 
 
 
 
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1996, 400, auto, capacitors, chicago, defog, ecm, ecu, flashing, light, ls, ls400, replace, replacing, service

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