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So I installed my ECU today with replaced caps, quite a power difference and no horrendous smells from the exhaust anymore.
Accelerator is more responsive too.
With that said, looks like it's time to re-lube the speedo needles..
Do you guys know where to get schematics for ECUs? Toyota basically told me to use their online factory service manual for info on the ECU. I already have that and there is nothing about the actual ECU components. Im not sure the rep understand my request. Anyways, thats what Im looking for now. Technical schematic for a 1996 Toyota 4runner A/T 2WD ECU. Let the hunt begin,
When you find one I want one too. There is zero, zilch, nota, nothing as far as schematics for any component in these cars or for that matter any car that I know of. I would like the same for all the ecu's in the car as well as the sound system. I guess all the out fits that do ecu repair have pretty much reverse engineered the things, and reinvented the wheel so to say, as far as repair schematics and instructions of how to. I think its crazy for Toyota or whom ever built the electronic black boxes in these old almost antique cars, to continue to keep it all a huge big secret. Doing so accomplishes nothing, not even will it cause the car to slowly die and then force someone to purchase a new car why? Because you have a choice of tons of aftermarket power train control systems. So what is with Toyota or Lexus for keeping this info from the enthusiasts that would like to learn more and keep their history alive? Wake up Lexus.
Well I tried. I got as far as the manufacturer and was road blocked with the whole "Its proprietary" routine. Its not like they are actually producing any new ones. Even the ones from the dealership are refurbished. I suppose a person could take a useless broken one for free and try to reverse engineer it. I dont even know how someone would go about doing that. Hypothetically speaking I guess a person could take really high quality images, then map out all the surface components. Remove those components and tray to remove board layers to scan/photograph all the layers and build a map. of course this would only be for a single model of a specific vehicle line. If it was cheap enough, it might be one of those "Challenge Accepted" moments.
Had a light go out in a Christmas carousel I had bought in the early 90's. Open it up to see what was wrong, and yelled "Yamae" as soon as I saw the leaking cap! My wife gave me a very strange look.
The image below is from the ECU of my 1993 LS400. Can anyone tell me what the two elements marked in red are? The first one looks like 'C772' and the second - 'IC770'. They both look like they need to be replaced together with the 8 large caps.
The image below is from the ECU of my 1993 LS400. Can anyone tell me what the two elements marked in red are? The first one looks like 'C772' and the second - 'IC770'. They both look like they need to be replaced together with the 8 large caps.
C772 is a ceramic capacitor and the IC770 is an integrated circuit which drives a power block. It's not easy to obtain those though.
I also must add that a visual inspection can't tell everything.
C772 is a ceramic capacitor and the IC770 is an integrated circuit which drives a power block. It's not easy to obtain those though.
I also must add that a visual inspection can't tell everything.
Thank you, Yamae-san! I agree with all. I have two more questions. Where can I find the PCB schematics for a 89661-50160 ECU so that I find out the value of the ceramic capacitor? Also, are UCF10 and UCF11 ECUs interchangeable?
Thank you, Yamae-san! I agree with all. I have two more questions. Where can I find the PCB schematics for a 89661-50160 ECU so that I find out the value of the ceramic capacitor? Also, are UCF10 and UCF11 ECUs interchangeable?
Unfortunately Toyota / Denso never releases any PCB schematics. We can't find any of them. All we need to do is the reverse engineering.
Regarding the changeability, as you see the lower part of the post #1, the traction control makes the difference but not the suspension for UCF10 and 11.
Hi,
Wondering if someone could help . I have been searching these posts for days and could not find a complete capacitor list for the 89661-24410 ECU for a 95 sc400 with the 94-95 federal ecu. Any help would be great. Id rather order them first then take everything apart and start the job when I could get to it. Thanks again
I just ordered 2 sets of caps for my sons 1993 LS400. The car recently developed an issue where it will not accelerate. The tach seems stuck and the temp gauge is slow.
I was thrilled to find this thread. Thank-you so much to everyone and in particular LScowboyLS and Yamae for lending their time and expertise to solving these nagging issues. The clarity and completeness of the instructions is an enormous help.
I found a local shop that will replace the caps for me. If the caps arrive before Saturday, I will take the ECU in then.
Curiously, the amplifier in the car was busted, which ended up being bad caps
I have a 1995 ES300 (1MZ-FE) and I was experiencing some of the problems listed above. When coming up to full temp, the car would randomly loose all power, the engine would idle but not rev properly and would die if you put it into gear, and it would throw a CEL (I later found this is likely the "Limp mode" but sadly it lacked the power to limp anywhere).
Initially I thought it could be a fuel issue, so I replaced the fuel pump and filter (~150$). The car worked for about a week then did it again. This time I had it scanned and the only code was a P0402 - Excessive EGR flow detected. After testing the VSV solenoid I found it to be faulty (no click when battery voltage applied) so I replaced it (50$). Car worked for a week, then same problem. I figured the EGR might somehow be getting stuck open randomly, so I bought and installed a new EGR valve (125$). Again, the problem returned. This time I removed the vacuum line to the EGR while it was acting up and there was no change to the idle, indicating the vacuum modulator was not the culprit. After replacing the EGR gas temp sensor (PicknPull) it happened again. At this point I have a brand new EGR system, and this obviously can't be the culprit.
Frustrated and considering selling my poor Lexie, I went to do more research and eventually stumbled upon this post. At this point I was already suspecting the ECU as this obviously wasn't an EGR issue and the symptoms didn't seem to make sense. I removed the ECU (who designed that freaking glovebox!?) and opened it up. Sure enough, 3 of the 6 caps were visibly leaking and corroded. This is the original 47uF Cap. Note it is already very tight with the blue resistor on the left, New cap is larger and touches here. Also thought this was a leak but it turned out to be glue. Damage left from leaking 100uF cap C120. Electrolyte stripped off the top coating and left a black scar of gunk. You can see gunk leaking from both 100uF caps at C120 and C115.
I ordered the capacitors you suggested, and went with all Chemicon caps. NOTE: the Chemicon 47uF and 220uF caps are significantly larger than original. My 47uF cap ended up touching the nearby resistor, not ideal but probably wont be an issue.
After some trial and error I managed to remove the old caps, clean up the board, and install the new ones. One mistake I made was to try and wick up all the solder first before removing the caps. THIS IS NOT THE WAY TO GO! The blob of solder transfers the heat, and without a good portion of this it really difficult to melt the solder completely and free the leads. Tin your iron first, lightly touch the solder joint with a flux pen to get a little flux on it, then just place the soldering iron below the lead to melt the solder while rocking the capacitor to the side to release the lead from the board. I did this with the board on its side, pulling the capacitor with my left hand and holding the soldering gun with my right. USE A VICE IF POSSIBLE! This is tricky work!
Thanks again to LSCowboy and Yamae for this awesome post! ECU problems are a mechanics worst nightmare, and I never would have attempted this without this awesome guide.
P.S. Lexie started up with no problems and no CEL. The purported low-end power gains are REAL it drives like a totally different car and as been running trouble free for a month now.
I've been aware of this issue for some time - and in fact on my '94 I did check all the Cs for ESR at 100kHz. They all measured within an acceptable range for their value, so I left them well alone.
However, on my newly-acquired '98, I am now wondering if I have the start of a problem. I have experienced the flashing front demister light, and also, the "foot-to-output" transfer function is much different from the earlier car, in that you have to squeeze the throttle a bit before it takes off, but then, boy does it take off!
Is the early UCF21 prone to stalling after high-speed cruising as is the UCF20?
Another thing, probably cap-related, is that I sometimes see patterning (scrolling bars of varying illumination) on the touchscreen. Is this also a known issue?
11-10-16, 02:19 AM
it drives like a totally different car and as been running trouble free for a month now.
