Hi all,

It turns out that our fabulous Bose stereo amps are not the only things that have capacitor failures over time. I happened to stumble across a couple of good articles on ECU problems on TechnoMotive's site, one of which is how to replace the electrolytic capacitors in your Electronic Control Unit (ECU). And Guess what? Some of the capacitors they're talking about replacing in the ECU are the SAME ones found in our Nissan Bose amp units. The cap replacement article even gives engine symptoms to look for if your ECU is playing tricks because some easliy replaced capacitors went bad.

89-94 ECU capacitor replacement


I was unable to link the cap repair article from TMO's main page, so I'm not sure what cars this ECU repair is for, but it looks like good reference info no matter what.

Here's another article on basic ECU operation from the same site:

ECU basics

Looking around TMO's site a little, I found a lot of other good info. If the above two article interest you, try browsing the whole site.
www.technomotive.com

Hope this helps some of you.

 

It never occured to me that the ECU would have caps in it. Seems logical though. Nothing is made to last.
I tried to repair a master switch by replacing the caps. It was a pain in the a$$. The switch had surface caps and I couldn't find any. I replaced them with regular caps and it kind of worked.

 

usually surface mount camps don't go bad nearly as much as the large electrolytic ones like these.
BTW, digikey has almost any cap you'll ever need as far as surface mount stuff.

so far, I haven't seen much of this happening on Maxes, but it might actually explain the VE stalling problems some people have seen where they're just cruising down the road and the engine stalls. dunno though.

most of the problems I see on nissan electronics are solder connections going bad on high current traces and components.

 

What got my attention was two things:

a) caps he listed for the ECU WERE electrolytic capacitors. Some of those were the exact same rating as those used in the Bose amps. I'm working on my Bose amps now which is why I caught this.

b)The caps used in the Bose amps have low service ratings - some of them are only 1000 operating hours, others are 2000 operating hours. So its easy to see why the electrolytic caps fail in just a few years. That makes it amazing we haven't had more ECU problems than we know about - If our ECUs use electrolytic capacitors. If you drove your car and average of 2 hours per day, You'd be over the 1000 hours cap rating in 1.4 years.

Granted, I don't know how applicable that tutorial is for the Maxima ECU, as I couldn't determine which car manufacturer ECUs he was talking about; and I haven't seen inside our Maxima ECU's either. So I may be 'crying Wolf' for nothing.

The next time somebody here in 3rg gen pulls a Maxima ECU, it would be worth the time to pull the cover an look to see if our ECUs use the same 'can type' radial electrolytic capacitors shown in the tutorial. If so, we need to add them (and ECUs) into the diagnostic conderations when engines are doing funny things.

 

When I looked at the master switch caps I wasn't sure if they were bad or not, looked like they had leaked, so I took it to the electronic store. The guy told me they had leaked, but he didn't know if changing them would solve the problem. They didn't have surface caps. He showed me how to replace them with the regular caps. Hardest part was taking off the surface caps. Now it works sometimes, before it didn't work at all.

 

i have some maxima ecu's laying around. i'll pop the cover off of mine again and take some pictures.