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

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LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

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

 
Old 11-28-18, 09:50 AM
  #1516  
RA40
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For the 42-48 MPH, that is a dead spot between shifts. The transmission may be hunting to select the right gear. To add to this, broken-worn engine and transmission mounts may exaggerate that sensation.
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Old 11-30-18, 02:00 PM
  #1517  
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1994 LS400 started running like crap every now and then. Chugging and hesitating. Did the normal stuff. Plugs wires cap rotor. Still had problem. Wife drove it and it left her stranded so I figure its time to pull ecm and looked inside. Burnt in between 2 capacitors right lower of picture. Can it be repaired or better off finding another one?
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Old 12-04-18, 10:17 AM
  #1518  
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Originally Posted by RA40 View Post
For the 42-48 MPH, that is a dead spot between shifts. The transmission may be hunting to select the right gear. To add to this, broken-worn engine and transmission mounts may exaggerate that sensation.
Well the recap fixed this issue as well. The rpms on start are still a little high and I am going to change out the coolant temp sensor soon and go from there( it is not 2,000 anymore it is around 1,000 but once it is drove a little it idles around 500-600). I also have a vibration at around 55 that once it starts does not stop till i get down to around 15mph and does not always come back but can be made to start again...thinking that one of the back struts are bad making wheel hop but am leaning more towards the trans mount. Thank you guys. I will update in one of the more appropriate threads when I figure out the vibration issue.
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Old 12-05-18, 06:17 AM
  #1519  
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Originally Posted by squeek158 View Post
Well the recap fixed this issue as well. The rpms on start are still a little high and I am going to change out the coolant temp sensor soon and go from there( it is not 2,000 anymore it is around 1,000 but once it is drove a little it idles around 500-600). I also have a vibration at around 55 that once it starts does not stop till i get down to around 15mph and does not always come back but can be made to start again...thinking that one of the back struts are bad making wheel hop but am leaning more towards the trans mount. Thank you guys. I will update in one of the more appropriate threads when I figure out the vibration issue.
More than likely your transmission mount. Take a look at the picture in post 88 in this thread. If you look at the mid upper left side of that picture you can see where the mount splits. Take a look at post 100 in that thread to see the before and after. The vibration in my car was bad from 45 to 55 MPH.
https://www.clublexus.com/forums/ls-...w-owner-6.html
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Old 12-11-18, 04:57 AM
  #1520  
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also make sure your throttle cables are in good shape
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Old 12-16-18, 04:10 PM
  #1521  
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Originally Posted by sam12345 View Post
I'm thinking solid state capacitors this way no liquid to leak. Also higher temp rating

http://www.avx.com/docs/Catalogs/tap.pdf

http://www.digikey.com/scripts/dksearch/dksus.dll

http://www.digikey.com/scripts/dksearch/dksus.dll


They cost a lot more which is why manufactures do not use them
Solid State Capacitor? If existed, it should be in the Pico Farad range and it's useless for the ECU.
Do you mean Solid Titanium Cap?
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Old 12-16-18, 05:34 PM
  #1522  
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Originally Posted by cfan View Post
Solid State Capacitor? If existed, it should be in the Pico Farad range and it's useless for the ECU.
Do you mean Solid Titanium Cap?
LOL.
There are 330uF ceramic capacitors these days and widely available. When you use those, you need to compensate the feedback loop to avoid the oscillation though.
https://www.mouser.com/Passive-Compo...w5t7?P=1z0wrkt

There are 470uF ceramic capacitors too. But the voltage rating is up to 4V.
https://www.mouser.jp/new/taiyo-yude...n-470uF-MLCCs/
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Old 12-19-18, 01:12 PM
  #1523  
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I have a 2006 GS430, just sent it in to SIA, all of a sudden I was experiencing hard shifts when slowing down. I found it very hard to believe that the tranny was going. ( 230K miles ). What I read here from a few of you guys about the ECM made a lot of sense to me. Being a retired broadcast engineer your thread made perfect sense to me. I must say you covered it in detail...excellent job !
thanks
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Old 12-28-18, 09:40 PM
  #1524  
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Anyone knows whether Driftmotion uses the authentic capacitors as published in the link?
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Old 12-28-18, 10:51 PM
  #1525  
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Does not appear so. Their capacitors are all black. They only replace capacitors, they don't test ECU's. We just repaired one of their "rebuilt" ECU's last week and the customer's car did not start at all. Upon inspection many traces were damaged and corrosion was present all over the board. We plug all ECU's into cars to verify correct operation and repair any broken traces and use the "good" capacitors which are brown.

https://www.taninautoelectronix.com/...00-ecu-repair/
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Old 12-29-18, 10:57 AM
  #1526  
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My hard shift problem came on all of a sudden on my GS430. No way that this was a transmission problem, I have high mileage, but maintenance was always done on my transmission. As one person explained it was if I was hit from the rear when slowing down. ( 2nd and 1st gear ). I sent my ECM to SIA Electronics in Illinois. Waiting for it to come back. When you see an electrolytic cap leaking on the ECM module as I have seen in many photos here it means it is shot. The crud left on the board must be cleaned and removed. Good idea if you really look closely and make sure no lands are broken. Replace the caps, also inspect that no surface mount resistors have lifted from the heat and cold over the years. I should be getting my ECM back in the next few days. I'll shove it back in and post my results. If this is the fix i'll be very happy considering the repair was only $130.00. PLUG and Play, since this is the cars own ECM, no need to go to Lexus and have them swap the Prom or flash it. Also another problem I had with my car was when i was coming to a full stop it started to act weird, Ran rough and no response from the pedal. After a minute or so it smoothed out. This happened 2 weeks before my hard shifts started to occur and I immediately parked it in the garage to prevent any other damage to the tranny. I think that this was the beginning of my ECM malfunction. The ECM, PCM, and TCM all have different functions but yet they all are part of the ECM. module. It's responsible for just about everything in the car. Thanks to LSCowboy, he nailed it.
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Old 12-30-18, 07:49 AM
  #1527  
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Originally Posted by rjc13062 View Post
My hard shift problem came on all of a sudden on my GS430. No way that this was a transmission problem, I have high mileage, but maintenance was always done on my transmission. As one person explained it was if I was hit from the rear when slowing down. ( 2nd and 1st gear ). I sent my ECM to SIA Electronics in Illinois. Waiting for it to come back. When you see an electrolytic cap leaking on the ECM module as I have seen in many photos here it means it is shot. The crud left on the board must be cleaned and removed. Good idea if you really look closely and make sure no lands are broken. Replace the caps, also inspect that no surface mount resistors have lifted from the heat and cold over the years. I should be getting my ECM back in the next few days. I'll shove it back in and post my results. If this is the fix i'll be very happy considering the repair was only $130.00. PLUG and Play, since this is the cars own ECM, no need to go to Lexus and have them swap the Prom or flash it. Also another problem I had with my car was when i was coming to a full stop it started to act weird, Ran rough and no response from the pedal. After a minute or so it smoothed out. This happened 2 weeks before my hard shifts started to occur and I immediately parked it in the garage to prevent any other damage to the tranny. I think that this was the beginning of my ECM malfunction. The ECM, PCM, and TCM all have different functions but yet they all are part of the ECM. module. It's responsible for just about everything in the car. Thanks to LSCowboy, he nailed it.
A GS430 does not use any QAS capacitors in the ECU, you need to understand.
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Old 12-30-18, 10:16 AM
  #1528  
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My GS430 is a 2006. I pulled the ECU last week and sent it to SIA for repair. There are 4 radial electrolytic caps on that board. ( aside from SMD caps ) Wish I would of taken a picture. If there were no electrolytic s ( 4 of them ) caps present on that board then I wouldn't of sent it in. If I am missing something please enlighten me.
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Old 01-07-19, 12:33 PM
  #1529  
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Default Won't stay running

After after several attempts to redo the capacitors on my 92 SC400 Lexus the car starts but then immediately dies like the alternator dead I put a brand new battery in it it starts right up but then dies is it because one of my capacitors might be bad

Last edited by RA40; 01-07-19 at 11:05 PM. Reason: first post quote removed
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Old 01-07-19, 05:13 PM
  #1530  
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Default 2006 GS430 hard shifts when slowing down.

It started a few weeks ago, hard jolt in 2nd and 1st when slowing down. Transmission was smooth as can be prior to this. I immediately put it in the garage to prevent any damage. Reading what others wrote about the ECU made a lot of sense knowing that the electrolytic caps may appear to look good but indeed they are not. I pulled the ECU for a visual inspection and was going to change them myself, but to go out and get a good solder iron and cleaning products would take me time and money. I decided to send it away to SIA and for 130 bucks all 10 caps were changed. Got the ECU back and installed it. She started right up, no lights on dash, and its running as smooth as ever. Its been a week now, all is well. Thanks for good info here on clublexus.
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