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No, I have never informed you guys here that Toyota had changed the electrolytic capacitors in the 98+. Toyota/Denso had been kept using those QAS capacitors up to the end of UCF20/21 production. They have changed those to newer ones when UCF30/31 were started to manufacture. Read the thread again selecting what I have written and you'd know more.
What they have started to use for a 98-00 were ceramic capacitors of a new generation and newly designed processors. Those ceramic capacitors have bigger capacitance with the higher withstand voltage although the size is smaller. Newer processors were fabricated with the narrower design rule and the performance per watt was improved and this made it possible to work faster with less power. These two reduced the stress to those QAS capacitors.
We have to be still careful that the same series of QAS capacitors (PF) and (PR) were used for 98-00 models and they fail quicker than conventional ones. As far as I have experienced, the major initial problems among 98-00 were the strange AT shift problems. Changing those capacitors can fix the problem in most of the cases.
Yes,ive read the thread.Ive also done other research,and finding peeps saying the 97 and lower had more issues on the ECU.
I appreciate the reply,looks like smart money says send it out and get er done! I will reread the part about the guy in Montclair Calif who does them,he is literally not far down the road from us.
Hello, thanks for the informative post on the faulty ECU. It's one of the best I've ever seen! What if none of the capacitors are leaking? My car is experiencing many of the issues that you described but upon expecting the board I didn't see any leaking capacitors. Also, can I send my ECU to Yamae for repair? If not, do you know of a reliable company/individual that can repair it? Thanks
Hello, thanks for the informative post on the faulty ECU. It's one of the best I've ever seen! What if none of the capacitors are leaking? My car is experiencing many of the issues that you described but upon expecting the board I didn't see any leaking capacitors. Also, can I send my ECU to Yamae for repair? If not, do you know of a reliable company/individual that can repair it? Thanks
Taninauto is a vendor here that does the capacitor rework in the ECU for you. Although it is not leaking, I have heard the axial electrolytic capacitors have a life of 10 years. Mines were not leaking but replaced them anyways-engine idle and revs were more crisp
Add another vote of thanks to LSCowboy and Yamae for this great thread.I ordered my caps (95 SC 400) last Friday from Digikey and they arrived yesterday. It was super easy since LS Cowboy added links to the correct products.
Just in time too, because yesterday afternoon my O/D off light began blinking and the speedo needle stopped working. It's my DD, so we'll see what happens
after I install them this weekend.
I have a 2000 ES300, 134K miles. I had codes pop up for 2 SL1/2 shift solenoids, I tested the resistance from the ECM to the transmission and it checks out. Next step would be to repair the ECM. I read about the first 20 pages on this thread.
I removed my ECM, opened it up and it looks nothing like pictures posted in this thread. No more QAS caps I suppose.
My question would now be, what am I supposed to look for in replace of those QAS caps?
I have more close ups, but I cannot see anything obviously wrong with it, checked for burn marks and chip cracks, but can't find anything. The glazing on the chips looks like some kind of coating (not sure if from factory or repaired before?)
Any help will be appreciated!
I have a 2000 ES300, 134K miles. I had codes pop up for 2 SL1/2 shift solenoids, I tested the resistance from the ECM to the transmission and it checks out. Next step would be to repair the ECM. I read about the first 20 pages on this thread.
I removed my ECM, opened it up and it looks nothing like pictures posted in this thread. No more QAS caps I suppose.
My question would now be, what am I supposed to look for in replace of those QAS caps?
I have more close ups, but I cannot see anything obviously wrong with it, checked for burn marks and chip cracks, but can't find anything. The glazing on the chips looks like some kind of coating (not sure if from factory or repaired before?)
Any help will be appreciated!
Are you asking those LS400 people here about your ES300?
I'd ask your type of question at the ES300 Forum. But I can easily imagine how you are desperate and needing a help badly.
A 2000 ES300 does not have any QAS capacitors in the ECU and you cannot fix it just only changing capacitors. Your important first step is to check the driving current to the solenoid. It should be about 1A. In other words the ECU drives the solenoid sending about 1A of the driving current.
A 2000 ES300 does not have any QAS capacitors in the ECU and you cannot fix it just only changing capacitors. Your important first step is to check the driving current to the solenoid. It should be about 1A. In other words the ECU drives the solenoid sending about 1A of the driving current.
Hi Yamae, thank you for your reply and I posted here since this thread had a lot of activity.
How would you recommend checking if there's a driving current? That would mean making the ECU think the car is in 3rd/4th gear? Or is there a feature in techstream for this?
Hi Yamae, thank you for your reply and I posted here since this thread had a lot of activity.
How would you recommend checking if there's a driving current? That would mean making the ECU think the car is in 3rd/4th gear? Or is there a feature in techstream for this?
I don't know what the procedure would be for testing the current. Would that be opening the transmission pan and checking current at the solenoid?
You have written, "I tested the resistance from the ECM to the transmission and it checks out."
Judging from your statement, I believe you know which wires are going to the transmission from the ECU. All you need is to measure the current using a clamp ampere meter at the related line to the solenoid. Without it, you need to cut the line and insert a regular ampere meter there. It would be very convenient to have a clamp current meter to do electrical DIY jobs. Without knowing the current, it is not easy to step forward. There are some alternative methods to check the problem without measuring the current. One idea is to check the resistance of the solenoid as well as the capability of the driver in the ECU.
You have written, "I tested the resistance from the ECM to the transmission and it checks out."
Judging from your statement, I believe you know which wires are going to the transmission from the ECU. All you need is to measure the current using a clamp ampere meter at the related line to the solenoid. Without it, you need to cut the line and insert a regular ampere meter there. It would be very convenient to have a clamp current meter to do electrical DIY jobs. Without knowing the current, it is not easy to step forward. There are some alternative methods to check the problem without measuring the current. One idea is to check the resistance of the solenoid as well as the capability of the driver in the ECU.
Okay, Yes I tested resistance.
The requirements:
Resistance:
(a) SL1+ <–> SL1–: 5.3 ± 0.2 W
(b) SL2+ <–> SL2–: 5.3 ± 0.2 W
(c) S4 <–> Body ground: 13 ± 2 W
Results:
I was able to test S4, and that was good 11.2 ohms
For SL2, I received a resistance of 5.2 ohms.
For SL1, I received a reading of 5.1-5.2 ohms.
I'll look around for getting a clamp current meter.
I have repaired around 30 of these varying from not leaking at all to leaking so bad a 6.8v zener had turned silver and measured short, various SMD capacitors had their terminals corroded, an SMD PNP transistor had a terminal disappear and multiple tracks had also vanished. I have not found one be unrepairable yet.
My process is
1) Tin all solder joints to be removed. The leaking electrolyte can contaminate the solder making it brittle and not melt.
2) Use a desoldering station to remove all capacitors
3)Clean the PCB well with "Chemtools PCB and parts wash cleaning solution"and antistatic brush
4)Wash the PCB cleaner away with demineralised water
5)Dry the PCB with a hair dryer, slowly go over the board at different angles making sure it is never too hot to touch.
6)Let it sit for 15 minutes and repeat this process 3-4 times
7)Closely inspect and test suspect components in areas of contamination
8)Test all suspect tracks. I made a cheat sheet which shows which components should be connected where to quickly rule out broken tracks
9) Fix any broken tracks using fine enamelled copper wire
10) install replacement capacitors (I use Panasonic FC, some with higher rated voltage)
11) Another cleaning and drying process and let sit for 3 hours
12) If suspect, check replaced capacitor pins that connect to internal layers to ensure they are making contact with internal layer (Have drawn a diagram for this too)
13)Apply DCA SCC3 high temperature conformal coating to protect PCB and seal against dust/moisture
14)Allow 6 hours for conformal coating to dry and reassemble
I think thats everything. I may add the process of reapplying thermal paste to relevant components in future.
Hey guys, I bought a LS400 recently (1990 model) and it had a few issues like: O/D light flashing with speed sensor 1 bad, solenoid 2 and 3. plus a check engine light because of a bad O2 sensor. Car felt veeeery heavy like it didn't want to move and shifted weirdly plus RPM and speeds are below 0 and temp gauge is always cold with stuck odometer. I was thinking it could be the speed sensor which I replaced but no fix. I saw a lot of issues with the ECU online so I decided to unplug the battery to give it a fresh start (made solenoid codes dissapear and havent come back since) aaaaaand it made it worse. car shakes heavily when accelerating, shifts worse, smells bad now by the exhaust also. I took the ECU out and opened it and found 0 issues inside. I bought the reccomended caps from Yamae and LS cowboy and I plan to replace them anyways this saturday. Would that fix my cluster issues also or should I change the caps in the cluster also? (cluster is already out too).
So, I think my ECU is suffering from the dreaded capacitor issue.
I have a 1995 LS400
here’s the issues I’m experiencing
1: Sometimes after startup and releasing the parking g brake, when I shift in to reverse or drive, it gives a hard jerk in to gear. This does not always happen.
2: Sometimes when leaving a dead stop for a stop light or stop sign, the transmission acts like it is slipping. This is also intermittent and doesn’t always happen.
3: Motor feels weak for a 260hp V8. Especially when Inoress the pedal all the way down.
3: Air bag light intermittently turns on and off (The dash light for thei safety airbag). Sometimes it will even flicker.
4. Basically, almost all of the warning signs have happened. Is there any way to contact LSCowboy to send it for repairs since I can’t contact him on his Facebook page? (I’m currently riding out a 30 day Facebook suspension due to FB incorrectly autoflagging a post)
02-14-18, 07:17 PM
90 ls400 probably ECU issues?
