All my crazy Lexus issues SOLVED!! (ECU-leaking capacitor)
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Joined: Oct 2012
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From: MD
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.
Thread Starter
Lexus Champion
Joined: Dec 2011
Posts: 4,078
Likes: 87
From: Birmingham, AL
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.
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; Oct 13, 2012 at 08:13 PM.
Thread Starter
Lexus Champion
Joined: Dec 2011
Posts: 4,078
Likes: 87
From: Birmingham, AL
I lost my gas cap, but im not sure if that affects it, although that did happen with my wife's S500. Suggestions??
Last edited by LScowboyLS; Oct 11, 2012 at 02:53 AM.
This guy sounds a little too smart to be hanging out with the rest of us 
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.
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.
Driver School Candidate
Joined: Mar 2012
Posts: 31
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From: Michigan
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?
220uf-16v
Last edited by cndnate; Oct 11, 2012 at 03:38 PM.
Thread Starter
Lexus Champion
Joined: Dec 2011
Posts: 4,078
Likes: 87
From: Birmingham, AL
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?
Attachment 501425Attachment 501695Attachment 501426Attachment 501427Attachment 501695Attachment 501428Attachment 501695Attachment 501429
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; Jul 20, 2013 at 02:41 AM.
Driver
Joined: May 2012
Posts: 100
Likes: 1
From: none
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.
Last edited by LexterLS40; Oct 12, 2012 at 07:20 AM.
Rookie
Joined: Oct 2012
Posts: 51
Likes: 1
From: Virginia
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.
Im not totally sure if this is something just laying there or its a scratch on lexters picture next to T802
Im not totally sure if this is something just laying there or its a scratch on lexters picture next to T802
Thread Starter
Lexus Champion
Joined: Dec 2011
Posts: 4,078
Likes: 87
From: Birmingham, AL
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!