Which capacitor does what?

[Matsumoto]

Hi all, hope your well and with the rain driving safely

I have 2 damaged and leaking capacitors in my ecu...

But does anyone know what the capacitor situated at number C512 does? I believe C810 is related to idle control valve? I'm hoping something here is related to my lack of injection pulse...got fuel to the rail and a healthy spark but the bores are bone dry as the injectors are not working...all 4.

I've checked all fuses/relays/earth straps/ etc etc

So hoping its this capacitor.

Hope someone can help thanks people

[markstevieandmads]

easy answer - replace the damaged capacitors (as they need doing anyway), repair any corroded tracks then try it out and see if it sorted your other problem!

[Matsumoto]

Lol yea I'm doing that anyway...but it's all on my mind...and while waiting for the things to turn up tomorrow id appreciate someone confirming it is most likely the cause at least I'll sleep easier lol

[Pauln]

For what it's worth I recently had to replace my ECU because both of those capacitors had leaked badly and damaged some of the tracks on the pcb.

The problem I had was that the engine management light was going bananas flickering and fading in and out, but the car was still running. So my suspicion is that C512 may be related to the OBD, but that's just a guess as so many things are interlinked on these cars.

As above, I'm afraid you won't really know if you've fixed your problem until you've repaired your ECU.

[Matsumoto]

Ok so I soldered in 2 new capacitors...and still no go.

I've got some PCB strips coming to fully repair the tracks but I'm getting continuity using a meter.... What is interesting though is that before I repaired the capacitors I had to move the car, on a whim I bolted the ecu back in and it didn't start, on trying to push her I started to crank her to ease the work do the 2 guys pushing and amongst all the bouncing around she fired up!

It ran for 10-15 secs then died. On tapping the ecu caseing I could get her to start and stall...

But since replacing the capacitors I can't get her to to do that now.? So loose wire in connector plug? Any ideas? I have the ecu in my and and using a meter I have continuity on the first 2 lugs top and bottom of the plug...anything else I can test using the meter?

I've tested the tracks which appear damaged and I have continuity there two but maybe it's too high resistance?

Any help would be grateful

[Pauln]

Just a thought, it's a double sided pcb and one of the pins on the cap (C512) on the smaller board needs to connect to tracks on both sides of the board.

It might also be worth double checking for dry joints. I found it really hard trying to get the solder to flow as I didn't want to hold the iron in place for more than 2 - 3 secs. You could also make sure you haven't been a bit rough with the flexible cables linking the two boards.

It could be a connector fault, but I would have thought it's more likely to be something to do with the repairs if this wasn't happening before.

I'd be interested to hear how the pcb strips work out because at some point I need to repair my old ECU as the rev 2's seem to be like gold dust. Do you have a link for them?

Paul

[Matsumoto]

Its ALIVE and all running sweet......

And its down to you Paul! after reading your post i decided to check what i had done, and as im relatively inexperienced in soldering ECU'S found i hadnt soldered the top layer....So many thanks for making me look!

But to anyone out there id give repairing it a go before buying a replacement, this has cost me £8.95

Thanks for your help

[Pauln]

Glad you got it sorted

Paul

[DB Mr2]

Hi Matsumoto,

Glad all is sorted for you
What revision/model was the affecting?
I have a rev2 turbo ecu that's faulty-the car fires but dies straight away.
I had a spare that I am using (and helped diagnose issue) but would like to have a go at fixing the ecu myself - was it hard to do I've never soldered a board before?

Thanks, Dan

[Matsumoto]

Hi Matsumoto,

Glad all is sorted for you
What revision/model was the affecting?
I have a rev2 turbo ecu that's faulty-the car fires but dies straight away.
I had a spare that I am using (and helped diagnose issue) but would like to have a go at fixing the ecu myself - was it hard to do I've never soldered a board before?

Thanks, Dan

Its a 93 Rev 2 turbo ECU number 89661 - 17380

it starts and then dies? how long this been going on go for?

[Matsumoto]

Because mine only played up once before.....then just died.

Its easy just open her up and look around....you will see if there are any damaged tracks or capacitors or anything by discolouration or corrosion.

My Capacitors where 10uf 50v (written on the side of them)- went on amazon and got 5 for 2.95 {panasonic}

just practice your soldering skills first on some thing first or look on you tube?

id upload pics but cant yet

[DB Mr2]

Its a 93 Rev 2 turbo ECU number 89661 - 17380

it starts and then dies? how long this been going on go for?

The engine was in my donor vehicle for turbo swap, after a month of not driving it would not fire up. Fortunately I had been building up spares for the turbo swap into my na and had a spare ecu. After initial fault fixing swapped them over and problem sorted. So the ecu has been sitting on a shelf waiting to be fixed. (Would be nice to have a working spare)

Your post has got me off my ar$e and made me have a look.
I have same ecu as you 89661-17380 and I just opened it up.
Both C810 and C512 have leaked so I will have a crack at replacing them
This is what I just found-similar to yours?

[Pauln]

You're in luck it looks as though you've caught it in time and hopefully the gunk hasn't done too much damage to the track underneath. It should be fairly straightforward to clean it up and replaces the caps, and with a bit of luck that may clear the fault.

This does seem to be a very common issue, so if you haven't already done so I'd also check your "working" ECU for similar issues as it won't necessarily fail immediately the caps start to leak. It's when the gunk starts eating into the tracks that things really get serious.

I obtained a working ECU for my Rev2 turbo recently, and before fitting it opened it up and found one of the caps has just started to leak, but fortunately hadn't done any real damage. So I changed both caps to hopefully avoid future issues. It does seem that any long lay off can speed up the process of these caps deteriorating.

Not the best bit of soldering in the world, but I wanted to make sure of continuity between left and right tracks when I replaced the cap.



Paul

[Matsumoto]

Yea that's pretty much it ...except my tracks where badly corroded, but where the capacitor legs are through the board, I had the same damage and black crap

[DB Mr2]

Cheers guys I've just bought 5 Panasonic capacitors from amazon and will change them over glad to hear mines not that bad.
If this works ok I will take out the working ecu and do that one as well

[tiff_lee]

I've found when doing pcb repairs if the copper pads in the immediate vicinity of the component is damaged and you're unable to solder to it then scrape some of the top lacquer off the board to reveal the copper track underneath, that way you can use some thin wire to 'jumper' from the through hole mounted component to the good part of the track.

[2mad]

I had two capacitors pop on my rev2 bored .. if you can swap them your self thats cost effective .. its just two caps go for it


I bought a second-hand ecu though .. price was right

[asdrewq]

Worth noting that you are supposed to use low ESR capacitors when you replace these. I could only find them in economical small quantities by ordering from digikey in the US (packs of 10 iirc)
It is a problem on many Toyotas of this vintage:

http://www.clublexus.com/forums/ls-1st- ... citor.html

[tiff_lee]

Urgh digikey, do they still have rip off shipping?

[2mad]

As long as the electrolytes have not killed the circuit bored .. get the caps swapped .. best idea