All my crazy Lexus issues SOLVED!! (ECU-leaking capacitor)
#991
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Last edited by kcHotRodLs; 10-27-14 at 09:49 AM. Reason: missing word
#992
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Did mine today, When I started the car, 2 of them blew. So, I read ALL the directions and replaced the 2 and this time let them pre-charge, (as the directions say to) and all seems well.
You hear a nice loud "Snap" when they go, so it's easy to tell.
The other thing I may have done is to not leave much space between the capacitor and the board. My old ones were not leaking, but 2 of them were stuck to other parts (melted plastic).
My main problem was jerking. my traction light has also been on for years, it is not on now. Since the jerking is intermittent, It will take awhile to see if it is solved.
The car also had no power, I bypasses the fuel pump relay and got most of the power back, I will now re-connect it and see is that had something to do with the ECU.
You hear a nice loud "Snap" when they go, so it's easy to tell.
The other thing I may have done is to not leave much space between the capacitor and the board. My old ones were not leaking, but 2 of them were stuck to other parts (melted plastic).
My main problem was jerking. my traction light has also been on for years, it is not on now. Since the jerking is intermittent, It will take awhile to see if it is solved.
The car also had no power, I bypasses the fuel pump relay and got most of the power back, I will now re-connect it and see is that had something to do with the ECU.
I did this repair on my '91 today. No problems, car seems to run fine now, but I guess it was not running too bad beforehand either. So I can't say it fixed everything, but it certainly did not make anything worse. We'll see if the engine code 25 comes back. I'll also be replacing O2 sensors (one done already) and the fuel filter just so I don't have to worry about those later.
EDIT - after a day, I can now tell there is an improvement. There were some minor glitches in shifting and idling that must have come in so gradually over the years that I did not notice them. I do now notice that they are all suddenly gone. Code 25 has still not returned. There were no significant visible signs of the caps leaking when I replaced them.
Post #1 right now calls for 11 capacitors for the 1991. I bought them all (several extras too) from Digi-key and searched and searched on the boards today but could only find 9 to replace. Post #1 currently says "1990-92 LS400 needs 10 or 11 caps as follows:"
Qty. 3 of 10μF - 50v - but I found only 2
Qty. 2 of 15μF - 35v
Qty. 3 of 47μF - 63v
Qty. 2 of 100μF - 10v - but I found only 1
Qty. 1 of 220μF - 16v
I found and replaced 2 on the left board and 7 on the right board. If anyone knows where the other two are hidden, please let me know. The 9 I found are all very obvious in the photos.
Some of the numbers on the label on the outside of my ECU are:
1750004110J
89661-50032
175000-4110 12V
1UZ-FE
0-467
As far as I know it is original and never opened before this.
I'm glad to have this done.
1991 LS400 ECU, left board, 2 caps
1991 LS400 ECU, right board, 7 caps
EDIT - after a day, I can now tell there is an improvement. There were some minor glitches in shifting and idling that must have come in so gradually over the years that I did not notice them. I do now notice that they are all suddenly gone. Code 25 has still not returned. There were no significant visible signs of the caps leaking when I replaced them.
Post #1 right now calls for 11 capacitors for the 1991. I bought them all (several extras too) from Digi-key and searched and searched on the boards today but could only find 9 to replace. Post #1 currently says "1990-92 LS400 needs 10 or 11 caps as follows:"
Qty. 3 of 10μF - 50v - but I found only 2
Qty. 2 of 15μF - 35v
Qty. 3 of 47μF - 63v
Qty. 2 of 100μF - 10v - but I found only 1
Qty. 1 of 220μF - 16v
I found and replaced 2 on the left board and 7 on the right board. If anyone knows where the other two are hidden, please let me know. The 9 I found are all very obvious in the photos.
Some of the numbers on the label on the outside of my ECU are:
1750004110J
89661-50032
175000-4110 12V
1UZ-FE
0-467
As far as I know it is original and never opened before this.
I'm glad to have this done.
1991 LS400 ECU, left board, 2 caps
1991 LS400 ECU, right board, 7 caps
#993
Moderator
My main problem was jerking. my traction light has also been on for years, it is not on now. Since the jerking is intermittent, It will take awhile to see if it is solved.
The car also had no power, I bypasses the fuel pump relay and got most of the power back, I will now re-connect it and see is that had something to do with the ECU.
The car also had no power, I bypasses the fuel pump relay and got most of the power back, I will now re-connect it and see is that had something to do with the ECU.
The power of the engine should be improved buy I worry about the your another problem. Bypassing the fuel pump relay simply means that the fuel pump is weak / fuel filter is clogged. The jerking of the problem is mostly caused by the insufficient fuel supply, as far as I have experienced. You can confirm it checking the fuel pressure.
#995
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In the directions it says to turn the ignition ON and let is sit for a couple of minutes before starting the car. I did not do this the first time, I just started it. One blew immediately and the second about 5 minutes later.
However I did not realize that there was a positive and negative terminal on the capacitors.
So, you are very possibly correct. When I replaced the 2 that blew, I matched the direction to one that had not blown.
So, if this was the case, I lucked out getting 7 of the 9 in the right direction in the first place. (or they will also go out).
Since I have a spare ECU, I think I will go ahead and replace the Capacitors in it now and pay more attention to the old ones positions and swap it with the one I just put in the car.
It does appear however that the jerking has stopped and the Traction light has not come back on. (after a 45 mile drive). I am going to re-connect the bypassed fuel pump resistor relay and see how she runs now. We head s
South for the winter, so the car will be sitting for the next 6 months, so the next computer swap will have to wait until spring.
However I did not realize that there was a positive and negative terminal on the capacitors.
So, you are very possibly correct. When I replaced the 2 that blew, I matched the direction to one that had not blown.
So, if this was the case, I lucked out getting 7 of the 9 in the right direction in the first place. (or they will also go out).
Since I have a spare ECU, I think I will go ahead and replace the Capacitors in it now and pay more attention to the old ones positions and swap it with the one I just put in the car.
It does appear however that the jerking has stopped and the Traction light has not come back on. (after a 45 mile drive). I am going to re-connect the bypassed fuel pump resistor relay and see how she runs now. We head s
South for the winter, so the car will be sitting for the next 6 months, so the next computer swap will have to wait until spring.
#996
Electrolytic capacitors do have a certain polarity, it is marked on them, if they are not installed correctly they will blow. As far as letting it set before starting, that should be necessary everytime the battery is disconnected then. I still don't understand the logic of that. I'm surprised connecting the caps wrong didn't wreck the ecu.
The most important thing to do when working on these is to have a wrist strap, the one I have I plug into the wall receptacle ground, that will make sure there is no static charge on me.
The most important thing to do when working on these is to have a wrist strap, the one I have I plug into the wall receptacle ground, that will make sure there is no static charge on me.
#997
Moderator
The most important thing is not have any voltage difference between the human body and the ECU. You need to connect the wire to the ground line of the ECU board.
#998
#999
Moderator
That's perfect, dicer. Sorry I didn't know that you connected yourself to both.
#1000
Im having problems with 2 of my ECU’s and I know it’s the ECU’s fault. I don’t have a LS400 but I do have a 92 SC400. 1 ECU with TRAC and 1 without TRAC. First ECU is throwing a code 52 (knock sensor). And no matter what I do, I continue to get that same code. I even switch the wires to the other knock sensor and continue to get code 52. Once the engine is off, the computer resets to NO check engine light … after driving for a few miles (5-10 miles) or up to 3k RPM, the check engine light re-appears causing the timing to retard. It also drinks a lot of gas. Second ECU, has a check engine light that will flicker and or dims out slowly. It will not allow me to check for codes. It runs perfect with NO actual problems affecting the engine. My question, is it possible these parts are the same for the 92 SC400 ECU’s? They are dirt cheap so I don’t mind buying 6 of each.
#1001
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Im having problems with 2 of my ECU’s and I know it’s the ECU’s fault. I don’t have a LS400 but I do have a 92 SC400. 1 ECU with TRAC and 1 without TRAC. First ECU is throwing a code 52 (knock sensor). And no matter what I do, I continue to get that same code. I even switch the wires to the other knock sensor and continue to get code 52. Once the engine is off, the computer resets to NO check engine light … after driving for a few miles (5-10 miles) or up to 3k RPM, the check engine light re-appears causing the timing to retard. It also drinks a lot of gas. Second ECU, has a check engine light that will flicker and or dims out slowly. It will not allow me to check for codes. It runs perfect with NO actual problems affecting the engine. My question, is it possible these parts are the same for the 92 SC400 ECU’s? They are dirt cheap so I don’t mind buying 6 of each.
On the first ECU, I would say it's all but certain that it is the cause of the knock sensor trips. Mine did that sporadically and it turned out the lower capacitor had corroded the input terminals below it ... corresponding to the knock sensors and O2 sensors. Zero such problems in the three months since. Also, the fact that your second ECU doesn't throw knock sensor codes rules out anything else.
I don't know what the issue is on the second ECU.
#1002
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Hi Yamae-San,
I am back because my intermittent problem is back. In your reply to me on 7/26 post #910 you suspected my problem maybe in my fuel pump area. My car failed recently after driving over 90-100 miles on a hot day and my '92 LS400 stalled in the middle of the road. I've already swapped my ECU in July so I am now looking at the Fuel pump system. My problem is intermittent and only when I drive long distance on a hot day.
Question that you may help me understand.
1. What is the purpose of the Fuel Pump resistor, P/N 28380A? I read somewhere another member replaced his FP resistor with good side effect to his radio audio it started to work and sound better, post #11 https://www.clublexus.com/forums/mai...em-solved.html
BTW, my radio audio has not been working for a while now. So I want to replace this part first because I want the good side effect with the radio audio working and per chance it may fix my intermittent problem due to hot condition.
2. Would you have the right version of the schematic of the Fuel Pump Relay/resistor for a '92 LS400? I've seen several versions posted in various threads. My mechanic and a second opinion could not read any diagnostic code from my swapped ECU right after my problem occured.
3. I replaced my original ECU (89661- 50032) with another ECU (89661-50042 w/ traction) from eBay in July after replacing the electrolytic capacitor. Is this the reason they cannot find a diagnostic code and does this have to do with the ECU requiring to be flashed with my car VIN? What problem will I possibly encounter with this ECU w/ traction? I now have replaced the electrolytic capacitors on my original ECU too. Should I swap back the original ECU?
4. I decided to replace the FP relay because I have over 185,000 miles. Part is on order.
I am disabled and It is not easy to get another replacement car because of special equipment. Another reason is I like driving my LS400. So I want to make the last attempt to fix my intermittent problem without spending a ton of money, and I want to be able to drive the distance without dying.
If the FP relay and FP resistor does not fix my problem, I am willing to replace the FP, a costlier undertaking.
BTW, I am having a tough time sourcing the FP resistor part for my 1992 LS400. Do you have any suggestions like a part number from Nippon Denso?
Yamae-San, thank you in advance for any help you can give and direct me.
Best regards,
Michael
P.S. Any help and answers I can get from the kind members is also welcome. Thank you too.
I am back because my intermittent problem is back. In your reply to me on 7/26 post #910 you suspected my problem maybe in my fuel pump area. My car failed recently after driving over 90-100 miles on a hot day and my '92 LS400 stalled in the middle of the road. I've already swapped my ECU in July so I am now looking at the Fuel pump system. My problem is intermittent and only when I drive long distance on a hot day.
Question that you may help me understand.
1. What is the purpose of the Fuel Pump resistor, P/N 28380A? I read somewhere another member replaced his FP resistor with good side effect to his radio audio it started to work and sound better, post #11 https://www.clublexus.com/forums/mai...em-solved.html
BTW, my radio audio has not been working for a while now. So I want to replace this part first because I want the good side effect with the radio audio working and per chance it may fix my intermittent problem due to hot condition.
2. Would you have the right version of the schematic of the Fuel Pump Relay/resistor for a '92 LS400? I've seen several versions posted in various threads. My mechanic and a second opinion could not read any diagnostic code from my swapped ECU right after my problem occured.
3. I replaced my original ECU (89661- 50032) with another ECU (89661-50042 w/ traction) from eBay in July after replacing the electrolytic capacitor. Is this the reason they cannot find a diagnostic code and does this have to do with the ECU requiring to be flashed with my car VIN? What problem will I possibly encounter with this ECU w/ traction? I now have replaced the electrolytic capacitors on my original ECU too. Should I swap back the original ECU?
4. I decided to replace the FP relay because I have over 185,000 miles. Part is on order.
I am disabled and It is not easy to get another replacement car because of special equipment. Another reason is I like driving my LS400. So I want to make the last attempt to fix my intermittent problem without spending a ton of money, and I want to be able to drive the distance without dying.
If the FP relay and FP resistor does not fix my problem, I am willing to replace the FP, a costlier undertaking.
BTW, I am having a tough time sourcing the FP resistor part for my 1992 LS400. Do you have any suggestions like a part number from Nippon Denso?
Yamae-San, thank you in advance for any help you can give and direct me.
Best regards,
Michael
P.S. Any help and answers I can get from the kind members is also welcome. Thank you too.
Last edited by mjkwee; 11-10-14 at 06:03 AM.
#1003
Moderator
Hi Yamae-San,
I am back because my intermittent problem is back. In your reply to me on 7/26 post #910 you suspected my problem maybe in my fuel pump area. My car failed recently after driving over 90-100 miles on a hot day and my '92 LS400 stalled in the middle of the road. I've already swapped my ECU in July so I am now looking at the Fuel pump system. My problem is intermittent and only when I drive long distance on a hot day.
Question that you may help me understand.
1. What is the purpose of the Fuel Pump resistor, P/N 28380A? I read somewhere another member replaced his FP resistor with good side effect to his radio audio it started to work and sound better, post #11 https://www.clublexus.com/forums/mai...em-solved.html
BTW, my radio audio has not been working for a while now. So I want to replace this part first because I want the good side effect with the radio audio working and per chance it may fix my intermittent problem due to hot condition.
2. Would you have the right version of the schematic of the Fuel Pump Relay/resistor for a '92 LS400? I've seen several versions posted in various threads. My mechanic and a second opinion could not read any diagnostic code from my swapped ECU right after my problem occured.
3. I replaced my original ECU (89661- 50032) with another ECU (89661-50042 w/ traction) from eBay in July after replacing the electrolytic capacitor. Is this the reason they cannot find a diagnostic code and does this have to do with the ECU requiring to be flashed with my car VIN? What problem will I possibly encounter with this ECU w/ traction? I now have replaced the electrolytic capacitors on my original ECU too. Should I swap back the original ECU?
4. I decided to replace the FP relay because I have over 185,000 miles. Part is on order.
I am disabled and It is not easy to get another replacement car because of special equipment. Another reason is I like driving my LS400. So I want to make the last attempt to fix my intermittent problem without spending a ton of money, and I want to be able to drive the distance without dying.
If the FP relay and FP resistor does not fix my problem, I am willing to replace the FP, a costlier undertaking.
BTW, I am having a tough time sourcing the FP resistor part for my 1992 LS400. Do you have any suggestions like a part number from Nippon Denso?
Yamae-San, thank you in advance for any help you can give and direct me.
Best regards,
Michael
P.S. Any help and answers I can get from the kind members is also welcome. Thank you too.
I am back because my intermittent problem is back. In your reply to me on 7/26 post #910 you suspected my problem maybe in my fuel pump area. My car failed recently after driving over 90-100 miles on a hot day and my '92 LS400 stalled in the middle of the road. I've already swapped my ECU in July so I am now looking at the Fuel pump system. My problem is intermittent and only when I drive long distance on a hot day.
Question that you may help me understand.
1. What is the purpose of the Fuel Pump resistor, P/N 28380A? I read somewhere another member replaced his FP resistor with good side effect to his radio audio it started to work and sound better, post #11 https://www.clublexus.com/forums/mai...em-solved.html
BTW, my radio audio has not been working for a while now. So I want to replace this part first because I want the good side effect with the radio audio working and per chance it may fix my intermittent problem due to hot condition.
2. Would you have the right version of the schematic of the Fuel Pump Relay/resistor for a '92 LS400? I've seen several versions posted in various threads. My mechanic and a second opinion could not read any diagnostic code from my swapped ECU right after my problem occured.
3. I replaced my original ECU (89661- 50032) with another ECU (89661-50042 w/ traction) from eBay in July after replacing the electrolytic capacitor. Is this the reason they cannot find a diagnostic code and does this have to do with the ECU requiring to be flashed with my car VIN? What problem will I possibly encounter with this ECU w/ traction? I now have replaced the electrolytic capacitors on my original ECU too. Should I swap back the original ECU?
4. I decided to replace the FP relay because I have over 185,000 miles. Part is on order.
I am disabled and It is not easy to get another replacement car because of special equipment. Another reason is I like driving my LS400. So I want to make the last attempt to fix my intermittent problem without spending a ton of money, and I want to be able to drive the distance without dying.
If the FP relay and FP resistor does not fix my problem, I am willing to replace the FP, a costlier undertaking.
BTW, I am having a tough time sourcing the FP resistor part for my 1992 LS400. Do you have any suggestions like a part number from Nippon Denso?
Yamae-San, thank you in advance for any help you can give and direct me.
Best regards,
Michael
P.S. Any help and answers I can get from the kind members is also welcome. Thank you too.
Regarding Q2, I don't have any.
I have no experience with Q3. I'd rather use the original ECU after replacing to recomended capacitors.
Regarding Q4, I would check the fuel pressure first before replacing the relay.
Last edited by Yamae; 11-10-14 at 06:28 AM. Reason: The link "fuel pump relay" is not my intention. It is done by the site.
#1004
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The purpose of the Fuel Pump resistor is to reduce the current to the fuel pump. This reduces the power of the pump and the amount of gasoline to be pumped out but it is still OK for the constant speed running up to the highway speed. The fuel pump relay works only when the extra gasoline is needed such as the running up a hill, a quick acceleration, a start up and etc.
Regarding Q2, I don't have any.
I have no experience with Q3. I'd rather use the original ECU after replacing to recomended capacitors.
Regarding Q4, I would check the fuel pressure first before replacing the relay.
Regarding Q2, I don't have any.
I have no experience with Q3. I'd rather use the original ECU after replacing to recomended capacitors.
Regarding Q4, I would check the fuel pressure first before replacing the relay.
#1005
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New issues ???
Replaced the caps in the ECU of my 92 SC300 over a year and 15,000 miles ago. Have taken it through 100 degree heat and 10 below cold, and the car ran like new..........until 2 or 3 weeks ago.
Problems similar to before, rough idle and strange instrument panel readings returned. Got to checking and strangely enough found that the alternator was literally filled with oil!!! Bad valve cover gasket was the culprit------- new alternator and gaskets fixed things and am back enjoying the open road.
Problems similar to before, rough idle and strange instrument panel readings returned. Got to checking and strangely enough found that the alternator was literally filled with oil!!! Bad valve cover gasket was the culprit------- new alternator and gaskets fixed things and am back enjoying the open road.