I must add some. In the past, I have fixed different ECUs and what I can say is that you have to be very careful for selecting the electrolytic capacitors. The internal impedance or the ESR is the key to select. The capacitance value was not very strict. Sometimes +200% did not cause any problem. For an example, I have used 100uF instead of 47uF and it was fully OK. But when I have used a regular type of capacitor, it did not fix some problem.
Those who could not succeed or who are about to fix the ECU, I suggest you to use low ESR type capacitors such as Rubycon type ZLH, Nippon Chemicon KZH, Panasonic EEU and other equivalents.
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Sorry technical question, were the original capacitors in the ECU rated at 85 or 105 degrees?
Are the affected capacitors coupling or decoupling?
I assume as the capacitors age their ESR increases and capacitance decreases which in turn produces more heat and the cycle continues until the heat causes the plug to push out of the base and the electrolyte then leaks from the capacitor.
I normally use a product called 'Safewash" which is a water based foaming PCB cleaner that does not leave any residue then use the iso alcohol drying off with a hair dryer.
Thankfully I still have supplies of lead solder and don't have to use the leadfree substitute which is rubbish.
the original capacitors are 105C, but far more important than temp rating is that the replacement caps are LOW ESR type!
I recommend 63/37 leaded solder for this job, and the safewash is fine but not necessary, vinegar and a soft toothbrush will clean the board safely as long as you follow that with a distilled water wash and then a couple of 91% iso-propyl alcohol washes
make sure you use one of the big Japaense cap brands - Rubycon type ZLH, Nippon Chemicon KZH, Panasonic EEU or Nichicon low ESR
inspect your work with a loupe afterwards
should be 6 or 7 caps depending on your model year, higher voltage caps than original are not necessary, but fine to use!
BE CAREFUL with the 4 ribbon cables that attach the two mainboards
ALSO - keep in mind that the capacitors do not have to be visibly leaking to be bad, therefore you want to replace ALL of them, even if they look fine!
please remember, when servicing the ECU caps, these 4 critical points:
1. replace ALL of the electrolytic capacitors, even the ones that appear to be fine, they don't have to be obviously leaking to be bad - there are typically only 6 or 7 in total - the 98-00 models have 10.
2. make sure the caps you use are LOW ESR type and 105C rated and voltage is at least the original rating.
3. stick with high end Japanese caps - Rubycon, Nippon Chemicon, Panasonic, Nichicon.
4. be very careful with the 4 ribbon cables that attach the two mainboards, if one of these comes partially loose then you have created yourself a lot more work.
Model: 94 LS400
So i dont assume right now the 6 caps that are needed for 95 and up ordered from nippon, etc would be enough to order until the write up is done? i would like to do the dash and ECU at the same time again thanks for the help everyone.
Qty. 2 of 10uF - 50v
Qty. 1 of 47uF - 63v
Qty. 2 of 100uF - 10v
Qty. 1 of 220uF - 25v