ECM Capacitor replacement?

[Malcolm99]

Anyone ever deal with Capacitor replacements on the 3rd gen 4R ECM?, seeing my CND 99' Limited has an OEM immobilizer and you must have the master key to program keys and FOBs to the ECM, I thought it wise to do some preventive cap replacement.

My question is has anyone done this before and created a write up?, and has anyone ever had problems with ECM Cap leakage. I realize any cap replacement will be similar, but curious if anyone has experience with the 3rd gen specific, and AFAIK all caps leak eventually and can ruin the circuit board.

I ask because I'm doing my 1992 Mitsubishi/DSM Eclipse 4G63T EPROM ECU again for the 3rd time as they seem to start leaking after 10-15 years. Below is the Mitsu/DSM/EVO VFAQ write up in the electrical section for example.

Visual Frequently Answered Questions - Home Page

 

[phattyduck]

I haven't seen many, if any reports of bad caps in 3rd gen 4Runner ECUs...

Probably for two reasons - Denso had figured this out and upgraded the capacitor quality by the time most 3rd gens were made.

And the less obvious one - electrolytic caps go bad when they are NOT used. 4Runners are driven regularly, so the caps degrade less than an equivalent your average DSM.

The '90's ECUs I have seen have cap issues are 'project' cars that are left unused for months/years at a time, not the regularly used ones.

-Charlie

 

[Pyral]

I've seen older Toyota's have capacitor problems. These 4runners are getting to the age where they'll start failing from age. Luckily they predate the capacitor plague, so leakage is not something I've heard of on these.

Make sure that whatever caps you put in are from a company like TDK, Nippon, Elma, Panasonic, or my personal favorite Rubycon.

I've had decks that were 50 years old with Rubycon caps that don't sound like trash and haven't leaked, so that's my personal recommendation.

And get it from a company like Digikey, caps are something that gets faked.

 

[Malcolm99]

Thanks guys, yes there is a link in there for digikey, we used them back in the 2000'.

Interesting that they are less likely to leak when in use as the electrolytic fluid thins when discharged. 105C panasonic seems to be common and what was used on my spare DSM Eclipse ECU, I'll just have to work out the microfarads for the 3rd gen and quantity, perhaps my removed 97 SR5 spare ECU is similar.

Now you are making me wonder how my old 90's Pioneer stack is holding up, I see mention that there was a plague of imposter caps during the early 90's, apparently Mitsubishi got ALL of them, lets hope Mitsushita and Denso had better suppliers..

I think I'm going to have to learn to do the circuit board work myself, very hard to get work like this done properly, I usually have to supply the caps to insure quality parts and then cross my fingers I get good work.

 

[Pyral]

Many were effected. The formula that caused all the problems was derived from a formula that was stolen from Rubycon, and incorrectly transcribed. This started around 1999, only electronics made in the last of the 90s are at risk, the caps can still fail but leaking isn't as common (varies by brand).

The capacitors used in cars are a special automotive grade capacitor (which your replacements should be btw), so that might be why it wasn't a problem like it was with consumer electronics.

 

[phattyduck]

caps can still fail but leaking isn't as common (varies by brand).

There's a big difference between the sudden and way to early problems of the early '00's and what the OP is generally talking about.

I have replaced the caps on a Toyota/Denso ECU due to leaking - it was on a friend's car... and that ECU sat for a long time with no power ('95 ST205 3s-gte ECU). My same ECU is still going strong with no issues 15 years later - but it has been powered and used regularly for the most part.

As PCB work goes, this is the simplest repair. A decent iron, solder, some solder wick and some flux remover to clean things when you are done is all you need. All the needed specs are on the caps, printed clearly. (yes, 105*C automotive grade should be used)

-Charlie