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 20V Leaking Capacitors in ECU....
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jondee86
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4374 posts [96%]
Wellington, NZ

 TECH: 20V Leaking Capacitors in ECU.... Reply  Edit


REPOST of Article from toymods.org.au by The Witzl

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Well, in lieu of all the guys replacing the dodgy Nichicon capacitors in their 1JZ
ecu's, someone suggested that I have a look inside my 4age 20V ecu to see if
it too used the same Nichicon capacitors that are known to leak electrolyte and
cause performance issues in 1jz and other japanese imported engines.

I would also suggest to ANYONE with a JDM Toyota ECU in their car to open the
lid and have a look for the suspect Nichicon capacitors!

Anyway... Here is my guide for replacing the caps in a 4A-GE 20V (silvertop) ECU.

Of course, we start by removing the top lid of the ECU, by undoing the 4 screws in
the corners. There might have a dob of glue in the screw heads, just remove this
with a pick of some sort.

Now you have the ECU open:
Immediately, I noticed a leaking cap up near the ECUs connectors. You cant quite
see it here, but there is black **** and corrosion all underneath this cap, and it's
pretty much damned the PCB (printed circuit board) tracks nearby.

Next... I wrote down a list of all the capacitor values, and their corresponding IDs
on the PCB. (near each cap is an ID no., eg. C012, C004 etc).I took that list to my
local Jaycar, and picked out some replacements.

The required caps are:

* 47uF, 63V x 2pcs - C002, C708
* 33uF, 35V x 1pc - C004
* 220uF, 10V x 1pc - C014
* 100uF, 10V x 2pcs - C017, C011
* 15uF, 35V x 1pc - C709

Shopping at Jaycar, you can buy direct replacements for all of the above, except
two.
- 33uF, 35V...... Jaycar only stocks a 33uF, 25V. I'm taking a risk with using a lower
rated voltage cap, you should replace with a voltage rating of the same or higher.
- 15uF, 35V..... 15uF is a very uncommon value. You can combine a 10uF and a
4.7uF cap in parallel to add their capacitance. More about this later.

Now, i set myself up with a de-soldering pump, soldering iron, replacment caps,
some solder, and some PCB cleaner NA1008 .... all from Jaycar.

Now, on the underside of the ECU case, remove the cover (just like the top lid).
Now, there are 6 screws holding the PCB to the metal frame of the ECU, remove
them. On the side of the ECU frame, there are 4 screws holding the power
transistors to the metal frame, using it as a heat sink. Undo these:

Now the PCB comes out of the frame!

Next.....
You dont have to do this step, but I attacked the underside of the PCB with the pcb
cleaner to remove the layer of protective lacquer. This lacquer is used to protect the
solder pads from corrosion and electrical shorts. Removing it helps with desoldering

It'll take a bit of PCB cleaner to get it off, and the pcb will start looking milky white...
dont worry, just use more cleaner!!

NOW...... we start removing capacitors!!!
This can be a little tricky if you arent handy with a soldering iron, but some patience
is always helpful. Start with one cap at a time, removing the old cap, cleaning up the
area, and replacing it with a new cap.

To remove:

1. on the underside of the PCB, heat up one solder pad where a leg of the dodgy
cap is coming through.
2. Now grab the solder pump whilst youve got the iron still heating the pad, and
suck up the solder whilst it's liquid.
3. Repeat for the other leg of the capacitor
4. Now denso were bastards when they made these ecus.. they bent the legs of
the caps over to make removal a PITA. Whilst heating the solder pad, use a small
flatblade screwdriver to bend up the leg of the cap. Repeat for both legs.
5. Now, grab the top of the cap with your fingers, and whilst heating each of the
solder pads (alternate between pads to keep the heat going). The cap will slowly
but surely come out.

6. clean up the area of any excess solder and other crap

Now... fit the new cap. BE CAREFUL TO TAKE NOTE OF THE POLARITY!! The PCB
indicates which side of the cap is negative, match that up to the "negative stripe" on
the new cap. Dont get it reversed, or the new cap will blow when you power up the
ECU.

See here for how to get it right. Note the negative stripe on the new cap and the (-)
mark on the PCB?

Now when you get to the 15uF nichicon cap, things get a little tricky. Get your 10uF
and 4.7uF caps, and before you fit them to the PCB, solder the legs together in
parallel. This effectively makes a 14.7uF cap! Trim off the excess legs from one of
the two, so that you only have one pair of legs left. Now fit them like so:

Now... because of the harsh vibration and whatnot your ECU will endure, its
probably a good idea to use some hot melt glue to stop this multi-cap from vibrating
and breaking the solder joint.

Now where i had that leaky cap, the PCB track was ruined. So i "replicated" the PCB
track using a piece of wire. You may not need to do this, but i'm over cautious.

Now... after replacing all the caps, i gave the PCB a quick coat of PCB laquer,
NA1002 from Jaycar.... let it dry, and put it all back together.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Note that the larger images from the original post seem to have been lost. These
small ones were all I could find on the interweb... still, better than none

Cheers... jondee86


Modified by jondee86 at 8:36 AM 2/6/2011



jondee86 has been a member for 735,126 days.

Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.



sp20v
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424 posts [89%]
Khi Sind

 Re: TECH: 20V Leaking Capacitors in ECU.... (jondee86) » Reply  Edit


I Have a Look On Mine's And It Looks Ok.....In BT ECU's That Transistor For VVT also Tends to blow/fail.......!!
B.t.w Solid Caps Are Better Than Those electrolytic ones....!! if anyone replace try finding solid caps for Win



DOHC 20v'D
Crownvicman289




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1984 posts [58%]
Colorado Springs CO

  » Reply  Edit


How would the car act to give you an indication of leaky caps?
jondee86
Reggae Rules...



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4374 posts [96%]
Wellington, NZ

 Re: (Crownvicman289) » Reply  Edit


Very common problem with AE101 ECU's. Causes all sorts
of mostly random issues. When weird stuff starts happening, it
is always worth taking the lid off the ECU and looking for two caps
with dark staining around them on the PC board. Some symptoms...

- problems in getting into diagnostic mode
- random dropping into "limp home" mode
- throwing random fault codes
- engine won't rev out/rev limits at 2000 or 3000 rpm
- engine runs like crap
- random not starting or cutting out
- low idle or erratic idle

Cheers... jondee86



Modified by jondee86 at 8:38 AM 2/8/2011



jondee86 has been a member for 735,126 days.

Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

Jeonsah
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Co

  » Reply  Edit


This thread smells like stickie



WTB AE86 Best Motoring International Vol. 42. Pm if you have it!
Crownvicman289




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1984 posts [58%]
Colorado Springs CO

  » Reply  Edit


- random not starting or cutting out

I'll have to take a 2nd look at my other BT ECU, I might be able to save it. This is exactly what it did, left me stranded. When I went to trailer it home, it fired up and ran perfectly. Swapped ECU's and never looked back.

HASportAE86
IE Gutter Trash



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4096 posts [84%]
Loma Linda CA

 Re: (Jeonsah) » Reply  Edit


Quote, originally posted by Jeonsah »
This thread smells like stickie

Sticky Po-lease





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s24a
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Canton Michigan

 Source for capacitors » Reply  Edit


I have performed this swap on both my Silvertop ECUs.
Ifound all the capacitors, including the elusive C004 (33uF 35V) and C709 (15uF 35V) at Digikey.

Additionally, I got the extended thermal range versions from Panasonic......

elmerkit
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351 posts [100%]
carson la

  » Reply  Edit


Leaking capacitors can lead to erratic idle and very rich timing, this is common to 4age st ecu.



"On sale Itp tires and ATV tires"

SDfanatic
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San Diego CA

  » Reply  Edit


ok this sounds just like what my car is doing right now! I actually just posted a "HELP" post couple days ago to give me guidance as to diagnose the problem. However, I suspected it was the fuel pump because after filling it with gas it died as i was driving home.

If it is the ecu, can I send it to some of the members on here who have experience in doing this capacitor swap? Of course Ill pay for the services, I just need this problem resolved asap

s24a
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Canton Michigan

 Re: (SDfanatic) » Reply  Edit


The way to tell (as above) is to open the ECM and examine the caps in question to see if they are either leaking (obvious) or if they are "bulged" (the top of the cap is bowed upwards and not flat).

Either condition indicates that the Nichicon cap is bad.

Regarding replacing these caps, I can do this operation, as I have extra capacitors.

However, I do like to see the circuit board up close to see if there are ant damaged tracks (one of mine had an open ground trace, evidently due to excessive current that may have been as a result of the blown capacitor(s) in it).

If so, I would have to trace and repair that as well, which can be done, but I don't have a test bench to confirm the repair.

If you are still interested, PM me for details....

Red




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 Re: TECH: 20V Leaking Capacitors in ECU.... (jondee86) » Reply  Edit


"I'm taking a risk with using a lower rated voltage cap,"

Absolutely. Since alternator voltage is 14.4 volts, the caps should be rated for a minimum of 28 volts by standard engineering convention. (Which will probably mean 30 volt).

You can get just about any cap you need from http://www.digikey.com or http://www.newark.com, that's Digikey or Newark Electronics. Two of the largest parts suppliers in the business and you can call either one to get human assistance with questions like "What's the best brand you carry?" and get a straight answer.

They (and even Radio Shack) also all carry tools called "solder suckers" or "solder removers". To get the excess solder off connections, so the part is MUCH easier to remove, you heat the solder up and then place the solder sucker right on top of it. It looks and works like a spring-loaded syringe, when you pull the trigger it goes "POP" and sucks up the liquified solder. Probably $10, even a plastic one will do for non-occupational use.

You can also use "desoldering braid" to do this. This is a fine braided copper wire, like a grounding strap, that has been fluxed. When you touch it to hot solder, the solder grabs and soaks right up into the braid. As the braid fills, you cut it off and throw it out. So for small jobs, or one-shots, the braid is fine, and a little easier to use than the solder sucker, but it will cost more in the long run because it is consumed as it fills up.

Get the right tools, they'll make the job way easier, and they're not expensive.



--Original owner, '85 Corolla GTS. Will trade for a Cadillac-Gage V150, or a Ford GT, in similar condition.
adammtb
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Asheville NC

 Re: TECH: 20V Leaking Capacitors in ECU.... (Red) » Reply  Edit


S24A...I think I need your services. I think I sent a PM but I'm not sure. I only found a function called IM...is that the same thing? I have a 20v ST and I just pulled my ECU to find what I think is a leaky capacitor. Can you help? Could you PM me if what I did was not the PM?

Thanks

adammtb
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45 posts [100%]
Asheville NC

 Re: TECH: 20V Leaking Capacitors in ECU.... (jondee86) » Reply  Edit


Look what I found when I pulled my ECU...damn!


Red




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9661 posts [78%]

 Re: TECH: 20V Leaking Capacitors in ECU.... (adammtb) » Reply  Edit


Yeah, that's a leaky cap.

If you can't replace an ECU ($$) but you can find any kind of "tv repair" or "radio repair" shop still in business...for them this is just another routine circuit board repair, doesn't matter what the board came from. Expect to pay about $75/hour for them to repair the board, and somewhere between $1-5 each for the caps. Probably a $50-100 repair depending on how they feel.

(Yes, it is possible for someone who has no experience with these things to destroy a board, heads up to those with no soldering experience, this is not the place to start learning.)



--Original owner, '85 Corolla GTS. Will trade for a Cadillac-Gage V150, or a Ford GT, in similar condition.
SDfanatic
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San Diego CA

  » Reply  Edit


ok s24a we need your help! I understand the concept of soldering and de-soldering but like Red said im not trying to destroy my ecu board. Please email me details as how I can send u my ecu @ nmsd77@gmail.com thks in advance

--Nick

alexkcloe
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Seri Kembangan Selangor

 Re: TECH: 20V Leaking Capacitors in ECU.... (jondee86) » Reply  Edit


thanks jondee.
I have replaced a new RUBYCON cap with 105C capable.
Right now ECU back to working condition.
My second unit ECU's had a same problem too and at the same cap's. The cap is leaks. Intermittent engine check lid's, and under power is run's. Seems the gear box working in 3 gears all the well.

Some mechanic said it's a very common issue to the silver top engine. And, it's may cause the wiring issue.

Right now, I still have no confident that to the repaired ECU's how long its can be last?

Any how it is appreciated that your valuable advice.

Red




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9661 posts [78%]

 Re: TECH: 20V Leaking Capacitors in ECU.... (alexkcloe) » Reply  Edit


Alex, there have been many problems caused by a particular Chinese cap maker who were too cheap to be true. And electrolytic caps tend to fail more easily than many other parts. But when the parts & design are good these things can expect to work literally for a lifetime.



--Original owner, '85 Corolla GTS. Will trade for a Cadillac-Gage V150, or a Ford GT, in similar condition.
tantrumdoc
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 Re: TECH: 20V Leaking Capacitors in ECU.... (jondee86) » Reply  Edit


i have no solution to ur prob but i wonder if anyone cud give me the website for the manufacturer of Freedom ecu. i know the company is E&E Sytems but i cant find a website
jondee86
Reggae Rules...



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4374 posts [96%]
Wellington, NZ

 Re: TECH: 20V Leaking Capacitors in ECU.... (tantrumdoc) » Reply  Edit


http://www.e-freedom.co.jp/

Good luck with that

Cheers... jondee86



jondee86 has been a member for 735,126 days.

Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

taroroot


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 Re: TECH: 20V Leaking Capacitors in ECU.... (Red) » Reply  Edit


I'll have to remember to check this when I get my 20V ECU back from loan. This is a classic problem with computer motherboards & flatscreens. Kinda interesting, from what I recall it was a case of industrial spying biting the company in the butt. Company stole electrolyte forumla that both companies thought was good, but was actually bad. Classic symptoms is equipment that randomly powers off, restarts, doesn't want to power on sometimes. If you've got the skills, you can score some good equipment for next to nothing! Friend's 40" plasma he got for free, well, less than $10 worth of replacement capacitor.
Hachiblue


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Seattle WA

 Re: TECH: 20V Leaking Capacitors in ECU.... (taroroot) » Reply  Edit


"several Taiwanese electrolyte manufacturers began using a stolen formula that was incomplete, and lacked ingredients needed to produce a stable capacitor"

http://en.wikipedia.org/wiki/Capacitor_plague

First heard about this problem on JZA70 ecu's when doing my 1JZ cressida. First encountered this problem when doing a 1UZ swap. Random fault codes and engine timing wouldn't advance. And now I think it's plagued my AE111 ECU. Revs up to 3500 rpm every start before dropping to normal idle even with ICV disabled, and randomly idles at ~600 rpm. Driftmotion.com repairs them for $80 I think if you are not willing to tackle the task yourself, they only list the 1JZ and 1UZ on their site but I'm sure they'd do 4ag's as well.

19223
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Salt Lake City ut

  » Reply  Edit


I believe I may have this problem, after replacing tps, afm, and a bunch of other parts I've traced it back to ecu electrical problems. I'm pulling my ecu tomorrow to check, is there anyone in the states offeing the service of replacing the resistors?
Red




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9661 posts [78%]

 Re: (19223) » Reply  Edit


Resistors rarely go bad. It is the electrolytic capacitors failing that were being discussed here.

Any electronics repair shop can test them or replace them.

Before you pull out the ECU, check the wiring from the AFM to the ECU, apparently there are some chafe points by the firewall and if one of those wires chafes and breaks, that's enough to stop the car from running. It will tuen over and fire up--but then quit as soon as you let go of the key.



--Original owner, '85 Corolla GTS. Will trade for a Cadillac-Gage V150, or a Ford GT, in similar condition.
fx-gt-boy


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  » Reply  Edit


Just recently iv been having problems with the way my car has been running and after coming across this topic iv opened up the ecu to find 2 of the capacitors leaking. After searching I'm really struggling to find equivalent capacitors .
The 2 that have blown are
Nichicon 100uf 10v PF(m) series
After further researching iv heard that the PF range was discontinued and replaced with the PJ series.
So iv been looking around for 100uf 10v PJ (UPJ1A101MED) but I can't seem to find any local.
Could I get away with running an equivalent range like the PM (UPM1A101MED)?
It seems to have the same ripple current but has a different impedence.
Would that work or is the anything else I could use?
Red




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9661 posts [78%]

 Re: (fx-gt-boy) » Reply  Edit


What is important here is the 100uF rating. You do not need a 10v part, a 12-25v part will work equally well, the voltage rating is a "do not use above this voltage" rating and while a 15v or 25v part will be larger, as long as it is 100uF it will be perfectly good here and function identically.

Digikey, Mouser, and Newark Electronics all carry them. Even Radio Shack should.

Two Digikey part numbers are 493-4491-3-ND and 493-4491-1-ND. If you use their search function, these are called "aluminum capacitors" rather than just "electrolytic capacitors", someone has hidden the product name. And these two happen to be 16-volt parts, they don't carry anything rated less.

The other two companies may carry 10v parts.



--Original owner, '85 Corolla GTS. Will trade for a Cadillac-Gage V150, or a Ford GT, in similar condition.
fx-gt-boy


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 Re: (Red) » Reply  Edit


Yeah I heard that I can get away with running a higher voltage.
Does the impedance and ripple current matter?
the discontinued 10v 100uf PF(m) is what im having to replace, the 10v 100uf PJ is what nichicon replaced the old PF series with but I struggle to get that one.

my local supplier can get me 10v 100uf PS, 10v 100uf PM or 10v 100uf PW. All of these have different ripple currents and impedance but if you say all that really matters is the 100uf and that the voltage is hight then does that mean I can run any of the 3 above.

iv got abit of a problem im trying my best to avoid buying from digikey, mouser and Newark as they have a minimum spend plus I'm in the uk so the main supplier I can use is rs components

Cheers

Red




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9661 posts [78%]

 Re: (fx-gt-boy) » Reply  Edit


I've never seen electrolytics spec'd any way except for voltage and capacitance, so I wouldn't think the ripple current matters. Still, I'm not an EE and I have no idea how bizarely Toyota may have designed the ECUs, so I'd try to get a similar impedance and similar or lower ripple current if possible. With ripple current, as long as you have the same or less than the original, that's what you ar elooking for. With impedance, you'd want as close to the original as possible, +-10% is probably good enough.

UK: Ah! Then you'd need a metric soldering iron, too.<VBG>

I have no idea what suppliers are in the UK, but 100uf capacitors are common enough that there must be multiple sources around. If all else fails, a tv/stereo repair shop or an amateur radio club should be able to give you a few names.



--Original owner, '85 Corolla GTS. Will trade for a Cadillac-Gage V150, or a Ford GT, in similar condition.
MazterDizazter


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259 posts [100%]
Marshfield MA

  » Reply  Edit


I replaced the capacitors in my ECU about a month ago; haven't driven the car much since, but I can say that it definitely helped. The car no longer bogs like crazy, but there's still some spotty areas in the midrange on occasion. I suspect that it's related to something other than the ECU at this point.



1987 Toyota MR2 hardtop
20v blacktop 4A-GE
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