Today my A4's ECU kicked the bucket

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Tejas
Actually, I dont know if it was mentioned yet. This error you are getting is familiar, check vwvortex. If you have an APR soldered in chip, the chip has gone bad or is not making full contact. If you dont have an APR solder in chip, then I guess this is not the case.
 
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Outside smalltown, IL
quote:
Originally posted by brianl703: That's very interesting about the ROM module being known to die. That reminded me that certain type of ROM, called an EPROM (Electrically Programmable Read Only Memory) has a finite lifespan--I've heard 10 years is what was guaranteed on those EPROMs that specified a lifespan. If it is an EPROM, there will usually be a sticker on the ROM chip which, if removed, will reveal a window through which you can see the actual chip. Exposing this window to UV light of the correct wavelength and intensity will erase the chip. EPROMs without the window are available to save costs, so lack of a window isn't a guarantee that it's not an EPROM. EPROMs have a limited lifetime because the bits are stored as charges in an insulated layer and given enough time, the charge leaks away, causing the EPROM to revert to it's unprogrammed state. When the chip is exposed to UV light, the UV light makes the charge leak away in a few minutes. The alternative to EPROMs, mask-programmed ROMs, do not have this issue because they are built with the correct programming inside of them--there is no charge to leak away over a period of years. Some automakers used mask-programmed ROMs and some used EPROMs. I don't know which, although I believe I read that Ford used mask-programmed ROMs. Mask-programmed ROMs are more economical for higher-volume applications, with EPROMs being more economical for lower-volume applications. This is all very interesting because, back about 10 years ago, I was kidding around with one of my friends telling him that his fuel-injected car will eventually lose the contents of it's EPROM chips. (At the time I drove a carbureted car..)
The life expectancy or an EPROM should be longer than the vehicle it's installed in. They should be effectively permanent in this application since you're not going though any program/erase cycles. A number of the old ECU's used socketed EPROM's and sometimes you'd have problems with socket corrosion. You could open up the ECU, pull the eprom and reseat it, cleaning the corrosion from the socket and IC legs and fixing the problem for a while. GM cars had this problem thanks to putting the parts in sockets. Ford avoided it by soldering the part directly to the printed circuit board. I imagine most the the newer ECU's use flash memory and again it should be permanent in this application. But, we have hundreds of modules from a certain company sitting around at work right now with bad flash memory. Just one date code has the problem of random bits losing their charge after a few weeks or months...
 
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10,910
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Nokesville, VA
Should be, but everything I've read indicates that EPROMs have a minimum life expectancy of 10 years, even when there are no program/erase cycles. I think the life expectancy of a vehicle can be greater than 10 years, so it seems to me that EPROMs might be failing before the vehicle does.
 

moribundman

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23,591
quote:
Actually, I dont know if it was mentioned yet. This error you are getting is familiar, check vwvortex. If you have an APR soldered in chip, the chip has gone bad or is not making full contact. If you dont have an APR solder in chip, then I guess this is not the case.
Marco, this is a non-chipped, stock Hitachi ECU for the 2.8 V6 12 valve motor. brianl703, I don't know if it contains an EPROM. I'll take a picture of the ECU's guts and you can tell me.
 

moribundman

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23,591
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Crappy electronics are the bain of Volkswagens/Audis. Great mechanicals, though. Actually, it seems that this is true of most German-designed cars these days.
My Audi hasn't had any electric issues apart from the dead ECU. The 1.8T has ignition coil issues. No problems with coils on a 2.8. If you think VW/Audi are bad with electric systems, look at BMW. Awful!
 
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10,910
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Nokesville, VA
quote:
Originally posted by moribundman: brianl703, I don't know if it contains an EPROM. I'll take a picture of the ECU's guts and you can tell me.
Sure, just post it here or PM me with a url where it can be found.
 
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Originally posted by Big O Dave: Actually, it seems that this is true of most German-designed cars these days. [Frown]
I'm still trying to figure out what it is with German, or European-designed cars and the wiring harness insulation. Some Jaguar, Volvo, possibly VW, possibly BMW, and Ford (both the Contour/Mystique and possibly the Merkur) models all have had problems where the wiring insulation becomes brittle and cracks off the wire, obviously leaving bare, exposed wire. In the case of the Jaguar and Volvo models, and the Ford Contour/Mystique, the problems are documented on various webpages. At least Ford did the right thing and offered a 10 year, 100K mile warranty on the wiring harnesses. I know that these problems are due to incorrect wiring insulation for the conditions the wire is exposed to. What I don't know is why this is such a problem with European cars, especially when Asian and domestic vehicles do NOT have these problems (the wiring harnesses on my 1988 Mustang are in mint condition).
 
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Alma, Michigan USA
Boys, I had my ECU, fail in my 1979 BMW 733i, in 1988. The techs at the dealer told me that you eliminate every other possibity and check all electrical questions, before replacing the ECU. Mine was made by Bosch, and my repair bill was around $1100., then. This is important! There is a fuse in the ECU, that can fail and should be checked out before you change that unit and cough up some big bucks. I don't know if these can be rebuilt or serviced in the USA, but someone probably is doing it. I would go on Ebay and but a used unit for $25., with some kind guaranty that it works. Have you inquired at an Audi dealer or Bosch certified service center, about a rebuilt? The wiring issue is caused by the harnesses being designed to be biodegradable, when they are scrapped. Nobil intentions, but they disintegrate before that time while still in use and on the car. Mercedes-Benz, is having big headaches with this on their big cars, but no recalls yet, but many mad owners, that won't be back as customers. To my knowledge, US and Asian cars don't have this problem. [Cheers!]
 

moribundman

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23,591
pastmaster, a new ECU for my car is $1,400 from a reputable online parts place, more from the dealer. A used one from a junkyard is about 600-800 bucks, with no warranty. The ECU is not considered a repairable item, but always exchanged as a module. Chances are that someone can diagnose it with the proper software and pinpoint the problem. As for the suggestion that I have to find the root cause of the ECU failure, which likely is due to a problem with the ROM module in itself as indicated by the diagnostic scan and what an Audi tech told me, it sounds like good advice, but beyond scanning, checking if everything is working properly,and thorough visual inspection of accessible wiring, I have hardly any way of tracking any possible cause. You know as well as I do how much wiring exists in modern cars. Let's not be so negative and instead hope that the new ECU will last.
 
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10,910
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Nokesville, VA
If it's an EPROM issue, a new EPROM can be loaded with the contents of another good EPROM. This will only be a possibility if it uses a standard EPROM. (Some ECUs may be using a custom-designed EPROM, which isn't compatible with the EPROMs available to mere mortals).
 
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239
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California
I had a ECU go bad on my 89 Volvo 240. Found another one at the JY for $25 from a different model and year. Works like a charm. Got to love old cars.
 
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10,910
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Nokesville, VA
If you don't mind, remove the two stickers that say MMS-411A on them and see if there's a "window" underneath. By the way, it looks like it's coated with that stuff which I think is used to make the board more waterproof. Ever Ford ECU I've taken apart has been coated with it.
 

moribundman

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23,591
I checked out those large ICs, but those "stickers" can't be peeled without destroying them. They are totally flush with the surface of the chip and I can't even lift a corner with a scalpel without causing damage. I assume they are EPROMs, because they look like those, but my curiosity ends here. As for the coating, it's the same stuff ("Platinenlack" -- circuit board lacquer?) I've used on circuit boards and electronic components back in the '80s when making my own electronic gadgets was my hobby.
 
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Nokesville, VA
The coating I'm talking about is in addition to the coating on the circuit board. It's on everything-board and components. It feels somewhat like silicone caulk when you run your finger over it--kinda rubbery, but it's a thin transparent coating. Those chips actually look more like a microcontroller with an integrated EPROM--they have too many "legs" to just be an EPROM.
 

moribundman

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23,591
The coating appears to be the same on the board and the components. It's not rubbery, but flakes fairly easily when scratched. But yes, the unmodifiable MMS-410/411 ECU has both the processor and memory program on the same piece of silicon. This makes that particular processor/memory set-up impossible to tune and maybe impossible to repair.
 
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