ECU repair
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Author:  asdrewq [ Fri Jul 05, 2013 9:38 pm ]
Post subject:  Re: ECU repair

I have personally seen this issue on 3 different rev3 mr2 turbo ECU's. As you have all found if you catch them early enough before the PCB tracks are toast you can do a fairly easy repair. IMO all MR2/Celica ECU's of this type will eventually have this issue. It's probably just that cap coming to the end of it's life and not any sort of inherrent fault.

Author:  Diceman [ Sat Jul 06, 2013 7:17 am ]
Post subject:  Re: ECU repair

Cheers cdb, as you say the poly will be massively bigger to the point of not fitting in the box!

It sounds like the main damage is caused afte the cap failure so the early inspection and replacement before the cap fails sounds like the best plan. A 10uf 50v cap is after all pence and could be replaced by any ham fisted soldering iron wielding monkey (I fit the bill) if the tracks are intact.

Now I need to find my ecu!

Author:  Nibbles [ Thu Jul 11, 2013 7:12 pm ]
Post subject:  Re: ECU repair

I had a quick measure round Doris's ECU tonight and couldn't find any tracks actually open circuit yet, so fitted to Daryls CS and it ran fine, no issues. Engine light worked fine - this is before changing the capacitors.

What symptome did you have Dorris ?

It is of course possible that the corrosion is through the track but in the warm weather with expansion the ends have pushed together again.

I'll clean up, replace capacitors and link across any tracks that have been attacked in case they go bad in the future then test again next week all being well.

Author:  Nibbles [ Wed Feb 03, 2016 11:08 pm ]
Post subject:  Re: ECU repair

Just adding a link to the 205 ecu thread by Phil before it gets lost in the mass.


Author:  Nibbles [ Tue Feb 16, 2016 9:48 pm ]
Post subject:  Re: ECU repair

Adding another thread on CCUK about the gen6 ecu. A few interesting points, particularly that the gen6 is a multilayer PCB which will make repair much harder if corrosion gets through the through plating. Also, it will require more care changing as a precaution as the through plating mustn't be damaged.

http://www.celica-club.co.uk/forum/inde ... cu-repair/

Author:  asdrewq [ Thu Apr 14, 2016 7:59 pm ]
Post subject:  Re: ECU repair

There is an excellent thread here discussing the issue in depth:

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

Author:  Diceman [ Sat Sep 10, 2016 8:50 am ]
Post subject:  Re: ECU repair

Another one bites the dust!
Project Arsey had started to occasionally flash the check engine light. - Fault codes were non-existent and just ignition on with TE1 & E1 seemed to set the car alarm off!

Having thankfully read about Chris' discovery a while back the first check was the ECU.

ImageImageimage by diceman2002uk, on Flickr

Cap was removed & Board Cleaned with solvent and then HPA. (I wasn't happy with teh cleaning job TBH but this was after 30-40 minutes with solvent & brush, some bits were like they had been baked in the oven for 2 hours and I didn't want to risk lifting tracks by scraping the crusty goop off.

Imageimage by diceman2002uk, on Flickr

New cap installed
Imageimage by diceman2002uk, on Flickr
Imageimage by diceman2002uk, on Flickr

Whilst I have tested continuity on the main 2 tracks I fear could have been damaged (E1 - R209) & (TVIS to R848) both seemed fine and tested OK. I am tempted to try fitting the ECU to test if I still have the CEL issue or maybe just install a bridging wire on E1 - R209 now.

Chris did say it's normally the big triangular area of track that suffers but I can't see which bit he means (Maybe mine has been eaten?)

Author:  Nibbles [ Sun Sep 11, 2016 8:16 pm ]
Post subject:  Re: ECU repair

The big triangular track is on the top board. You haven't shown any pictures of this so I'm guessing you've overlooked it.

Author:  Nibbles [ Sun Sep 11, 2016 8:19 pm ]
Post subject:  Re: ECU repair

p.s. The negative connection for the capacitor on the lower board is nearly always gone, and even if not you won't get solder to take on the corroded copper. I usually make this connection on the track side with a bit of wire up to the emitter of the nearby transistor.

Author:  Diceman [ Sun Sep 11, 2016 9:24 pm ]
Post subject:  Re: ECU repair

Cheers Chris,

The top board had been inspected and the capacitor had not leaked at ll. As in PM you indicated this capacitor was more likely the issue with CEL erratic behaviour I've just pulled it out anyhow, it measures around 3-4 nF so evidently dead and the same as the one that had already splurged.

Author:  Sirius [ Mon Sep 12, 2016 8:45 pm ]
Post subject:  Re: ECU repair

Interesting that they can also fail with no visible issues.

Author:  Diceman [ Tue Sep 13, 2016 12:43 pm ]
Post subject:  Re: ECU repair

Indeed Mike,
Electrolytic capacitors "drying out" is a common issue in valve amps and class A amplifiers due to heat but I hadn't expected to encounter the same issue in an ECU. I guess the ECU does contain a series of transistors and does heat up as a result but I know little about teh failure modes of electrolytic capacitors.

The main thing I can suggest however is that if any of you have an ECU and intend keeping the car I'd get the capacitors replaced before they start to eat the PCB tracks or show visual sign of failure. Whilst sourcing a replacement ST205 ECU may be a fair bit easier than a ST185 RC for the sake of around 40 pence of capacitors and a good drink to a friendly electronics nerd it is worth doing.

IMHO the most difficult part is trying to idnetify where the now non-existent PCB tracks should go! I'm hoping mine is still OK on the PCB tracks but it is still a PITA to try and trace the double-sided PCB tracks, especially when you have leaked electrolyte over the board.

I ended up using a garage LED inspection light under the PCB to trace the tracks and checked continuity with a multi-meter. You can clearly see where the tracks have been eaten.
ImageUntitled by diceman2002uk, on Flickr

Big thanks to Chris on this; without his write up and help I wouldn't have diagnosed or attempted repair.

Author:  Neil B [ Sat Sep 17, 2016 1:31 pm ]
Post subject:  Re: ECU repair

Just lifted the ecu out of my car and no surprise, it looks like the pictures
I'm hoping that this is the sole issue with the car now, or at least the issue that is preventing it running!
Any suggestions on someone offering a repair service? I really don't trust myself with a soldering iron!
Happy to pay obviously, well actually would insist on paying.

Have taken a couple of quick pics with the phone and can post them up later when I get home if they are of any interest to anybody

Author:  jeff [ Sat Sep 17, 2016 6:11 pm ]
Post subject:  Re: ECU repair

Your on the right thread Neil.
Hope someone gets back to you asap :)
It's a year or so since mine was sorted here xxx

Author:  Nibbles [ Sat Sep 17, 2016 8:08 pm ]
Post subject:  Re: ECU repair

I'm happy to do it for the cost of postage. I suggest using special delivery as this is tracked & insured, bearing in mind how rare these are. Usually about £20 each way. Drop me a PM if you want.

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