All my crazy Lexus issues SOLVED!! (ECU-leaking capacitor)
10-19-15, 12:51 AM
#1231
Driver School Candidate
Join Date: Oct 2015
Location: Virginia
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Dicer – actually I do understand, and I’ll match my undergraduate EE degree, graduate CS degree, and decades of telecom equipment H/W and S/W development against anyone concerning ESD. Now – do you have an answer to the potential failure of the SMD-profile aluminum caps?
10-19-15, 01:53 AM
#1232
Moderator
I have a 2000 ES300 with what I believe may be a similar issue with the ECM (leaky caps). It seems to have codes pop up out of the blue (e.g. – I’ve had P0325 and P0330 codes pop up regularly before and after I replaced the knock sensors and cable to them). It also see the check engine light (solid) and track (flashing) come up the A/C or heat on (does not show a code and resets when engine is turned off). Does anyone have a list of the caps I would need to replace or do I need to pull the ECM, get the current part number and possibly use the list of caps for the 2000 LS400 listed in the earlier post?
Some newer ECU boards sometimes have solder crack problems caused by the surface mounted big resistors which dissipate some big heat . The expansion rate of those are much smaller than the material of the board and the solder points are stressed and cause solder cracks, you must know.
10-19-15, 02:18 AM
#1233
Dicer – actually I do understand, and I’ll match my undergraduate EE degree, graduate CS degree, and decades of telecom equipment H/W and S/W development against anyone concerning ESD. Now – do you have an answer to the potential failure of the SMD-profile aluminum caps?
I'm not an EE just a lowly Fcc General radio.
Last edited by dicer; 10-19-15 at 02:21 AM.
10-19-15, 06:19 AM
#1234
Driver School Candidate
TomES300, I would like to help you with this but this type of board is out of my league. I have not dealt with any surface mount type capacitors. I have dealt with mostly the PF(M) type. Another reason I like the older cars, the newer ones are more complicated than a mortal man can fix. That said if you can replace them with the same uf rating and a equal voltage or higher as a last resort it might be worth a try. Yamae is right though it is probably not the capacitors causing your problem. I would listen to Yamae's advise as he knows this stuff much better than I do.
11-10-15, 08:01 AM
#1236
Driver School Candidate
I just did a 89661-30682 computer for a GS300, Here is a list of the capacitors I used for replacements. Two 10uf 50volt, Two 15uf 63volt, one 47uf 63 volt, Two 100uf 35volt and one 220uf 16volt. the voltage on some of the replacement capacitors may be higher than the originals but the uf ratings were all the same. I just used the recommended capacitors for the Ls400 for specific part numbers.
11-12-15, 05:00 AM
#1237
I just pulled apart my ECU, I got the same values except there are two 47uf caps.My ecu is a 175000-30690 93-94 GS300 Federal emmisions.
10uf 50v x2
47uf 63v x2
220uf 16v x1
100uf 10v x2
15uf 35v x2
When getting the values, I could tell at least 5 of them were leaking, so I will have to clean up the board before installing the new ones.I ordered them from Digikey. hopefully they are here Monday.
10uf 50v x2
47uf 63v x2
220uf 16v x1
100uf 10v x2
15uf 35v x2
When getting the values, I could tell at least 5 of them were leaking, so I will have to clean up the board before installing the new ones.I ordered them from Digikey. hopefully they are here Monday.
Last edited by williamb82; 11-12-15 at 05:17 AM.
11-12-15, 07:21 AM
#1238
Driver School Candidate
williamb82, If your capacitors were leaking you most likely found your problem. Your next concern is if the board got damaged. The traces are so small on these boards and if they are ate through new capacitors won't help. Don't be discouraged if new capacitors doesn't fix your problem if the board is damaged and bad. Just find a replacement computer and replace the capacitors. I have found a trend that computers from colder climates are going longer before the capacitors fail and leak, so if you need one look where it is from. Good luck
11-12-15, 10:20 AM
#1239
Yup, Im in Florida, No idea where these are from. Caps are cheap. I have 3 ecu's total, so going to change the caps in all of them. The very first ECU did the weirdest thing, Car died on the way home one night a few blocks from home. Opened the hood and I could hear the injectors clicking at random with the engine not running, so no RPM or cam/crank signal etc... I had a spare ECU at home so walked home, got it, swapped it in right there and it started and ran fine ever since, until this cold start issue. Swapped the ECU as I had already swapped in a new ECT, MAF, IASC, TPS, etc.. with no change. Verified the temp readings at the ecu connector for engine temp and air temp where correct. At this point it is running the exact same, so I dont think the traces are bad. it doesnt appear that the fluid ate through the green coating yet, but wont know for sure till I pull the old caps out.
11-12-15, 01:44 PM
#1240
Driver School Candidate
Williamb82, You might try pulling the codes from the computer. I assume it is the same as the ls400 and sc400. All you need is a jumper wire and a service manual for the procedure and codes. I had a code for intake air temperature on a ls400 and a sc400 and after several changes of mass air flow meters and the same code reoccurring I did an old trick I do to nissans in the late 80's and 90's. For some reason and I don't know why but it works an extra ground to the ground wire for the mass air sensor will get rid of the code and make them run better. On the ls400 and sc400 if you look at the back of the mass air sensor connector the ground wire is the one all the way to the right. About two inches from the connector I splice in a 14 or 16 gauge wire and ground it to the strut tower. This got rid of that code on both the ls400 and sc400 I have.
11-13-15, 05:24 AM
#1241
Nope, only engine code I get is the EGR, and it is intermittent. It shouldn't happen at all since I do not have an EGR temp sensor. This started a few weeks ago, the cold start issue was happening for weeks before that started. Also, I have an extra 4awg ground from the head to the body, and from the body to the negative terminal of the battery. I do this on all of my cars. My supras have been this way for well over a decade.
11-13-15, 07:24 AM
#1242
Driver School Candidate
Williamb82, Your problem is most likely computer related than in my opinion. If the new capacitors don't solve your issue I would ask Yamae for more specifics about the computer functions related to cold starting as he is definitely the expert in understanding these computers.
11-14-15, 02:53 PM
#1244
Parts arrived today. i changed all the caps in one of the ecu's and swapped it in. Starts right up and runs better, but the od off light is on, regardless of what the switch is set to, so apparently I messed something up. Gonna have to pull it back apart and check for a solder bridge somewhere or a bad trace on the board. Wish I could find a schematic of the ecu somewhere.
11-14-15, 03:30 PM
#1245
Moderator
Unfortunately both Denso and Toyota don't release the schematic of the ECU and other computer controlled units at all. All we need to do is to analyse the board by ourselves. This needs some technical skills and equipments tough.