EPROMS might go bad in old cars? "Bit Rot"
bill190
Posts: 769
I've been reading things like this about EPROMS going bad with age in old video games...
http://my.ais.net/~xtreme/SF/Bit-Rot/
And reading that the EPROMS used in vehicle engine computers will also eventually go bad when 20 or 25 years old?
Well I have a 1992 GM truck (21 years old) with a 2732 EPROM in its engine computer (still working).
I tried buying a new EPROM from GM and they have discontinued that part... I checked with a vehicle EPROM modifying company which sells "performance" EPROMS (goes faster and designed to run on premium gas) and asked if they also sell the original manufacturer coded EPROMS. They said they can't due to copyright infringement!
So I guess I will just have to copy my EPROM and write the code to a new EPROM. Not necessarily a big deal, but...
Apparently 2732 EPROMS are no longer made?
The specs for this EPROM are...
5 Volt 4K X8 DIP-24 450 Nanoseconds EPROM
I found some here which say "REFURB"...
http://www.jameco.com/1/1/3372-2732-eprom-4k-x-8-450ns-5v-dip-24-memory.html
So would that work? Or a newer replacement available?
And I don't have an EPROM programmer. Any recommendations on what to get? (Which could read and write an EPROM.)
http://my.ais.net/~xtreme/SF/Bit-Rot/
And reading that the EPROMS used in vehicle engine computers will also eventually go bad when 20 or 25 years old?
Well I have a 1992 GM truck (21 years old) with a 2732 EPROM in its engine computer (still working).
I tried buying a new EPROM from GM and they have discontinued that part... I checked with a vehicle EPROM modifying company which sells "performance" EPROMS (goes faster and designed to run on premium gas) and asked if they also sell the original manufacturer coded EPROMS. They said they can't due to copyright infringement!
So I guess I will just have to copy my EPROM and write the code to a new EPROM. Not necessarily a big deal, but...
Apparently 2732 EPROMS are no longer made?
The specs for this EPROM are...
5 Volt 4K X8 DIP-24 450 Nanoseconds EPROM
I found some here which say "REFURB"...
http://www.jameco.com/1/1/3372-2732-eprom-4k-x-8-450ns-5v-dip-24-memory.html
So would that work? Or a newer replacement available?
And I don't have an EPROM programmer. Any recommendations on what to get? (Which could read and write an EPROM.)
Comments
The ones from Jameco are probable "pulls" . The ones I have where programed once and pulled during prototyping. They where used once or twice.
Priority Mail should get a good turn around.
Jim
1) The charges on the storage cells leak away over time and your program gets corrupted.
2) The chip itself begins to fail due to things like "metal migration". Something that Beau has talked about here recently.
So I would imagine that in the case of a) one could simply erase the chip and reprogram your code back again and it would be good for another 20 years or whatever.
b) however is terminal.
Either way the first order of the day is to get a copy of the current code out of there and stored somewhere safe.
I have no idea but I would imagine the proms in engine controllers are not sitting in sockets waiting for easy removal and will have to be un-soldered. That in itself is a risky proposition to the entire ICU board.
Might not be too cost effective for a one off.
My offer is for free, (minus shipping).
Into a crude serial port so the internal rom could be copied. Look at so of the gm forums out
For modding ecms.
-dan
Offer still stands. I can order the 2732's and have them shipped here, then program, then send them off.
What say you?
Funny, it occurs to me that the ignition "computer" in my '67 Corvair is a one-bit processor, the breaker points inside the distributor. As the points wear, resistance increases and "bit rot" occurs; when the condenser value changes, metal migration occurs.
The more things change, the more they stay the same.
My Citroen BX19 GTi had ABS. Great feature but in years of driving that car I never needed it. Until one dark, rainy night...
I screwed up a bit and had to hit the brakes hard, there was an intersection where I was not expecting one to be. My fault.
What happened? The ABS failed at that moment and a yellow failure lamp lit up on the dashboard. I skidded out across the intersection. Luckily there was no one around and no harm done.
It cost me £300 to get that yellow light off so the machine would pass it's annual inspection. Seemed I really had to have a new ABS computer module. Ripping the whole caboodle out and having normal brakes was not an option.
"Great" I thought, "that yellow lamp will be off until the next time."
Thanks for the offer, but I also have several friends around here with the same trucks which they use daily. And there are many different codes for various years and models. So mailing them off would not be an option. Here is an example of all the different chips/coding for just 10 years of GM vehicles...
http://www.exatorq.com/ludis_obd1/c3xref.html
Actually mine looks like the top one in the following picture. It plugs into a socket on the engine computer.
OK, but it begs the question, why did you ask for help in programming another chip?
I was looking at the following for $70 (includes the magic word USB!)...
http://www.mcumall.com/comersus/store/comersus_viewItem.asp?idProduct=4225
I don't need help programming the chip, rather I want to pick everyone's brains about this EPROM "bit rot" problem.
And wanted to learn about old EPROMS no longer produced - perhaps a newer replacement is better?
And there are some great bargain hunters here, maybe some suggestions on EPROM programmers?
And also I wanted to mention this problem here. Some people here go WAY back and have all sorts of old computer games and so forth. So a "head's up" about this problem in case they want to save their EPROM data.
Just be careful when ordering a new EPROM. There are many variants of that chip and they have different programming voltages, (27C32, 27C32B, 27C32C, 2732A, 2732B)
Yes. Very happy to not need a computer diagnostic on my '63, '65' 69 VW's and recently on my '71 mustang.
Points and a match book....good to go.
Thanks. I also just read I should try to get an "industrial" temperature grade EPROM. That makes sense as the inside of a vehicle can get to be *very* hot!
-Phil
We're not exactly talking 'nanometre resolution' on the etch mask when the chip was made...
Your biggest problem is bit rot.
If 2732 chips are difficult to find, go for a 2764 or 27128 and just tie off an address pin or two.
(Or you could have several profiles on the same chip, and just switch between them when you feel like it)
Back in the 90s, a friend of mine made an 'EPROM Emulator'. Basically a static RAM chip and a battery on a small breakout board that gave it the same pinout as the normal EPROM.
It was a real timesaver when working with mCUs, as instead of having a few EPROMS that needed to be erased with UV light, all it took to erase was the flip of a switch. (Working with assembly code means reprogramming often... )
You're 'lucky', tough, that you can pull the EPROM from your ECU.
In the 1996 Magneti Marelli unit currently in my car, and the 1999 SAGEM unit I recently tossed out, everything is potted so completely that you can't even tell where the assorted chips are on the PCB. Frankly, you'd be hard pressed to get the PCB out of the metal casing without a chisel and a lot of brute force... (The b@strds probably added the removable metal panel just to spite tinkerers... )
Luckily though, the programming can be updated through the OBD II connector, if you happen to have the right SW and the appropriate images...
(Which by a lucky coincidence is installed on one of my netBooks... )
Drove the Mercer Island Bridge a few time when I live in Seattle.
Don't you have a few pic of the appropriate funeral of the Pinto? I can't seem to find them.
Sorry to steal the thread.
Matchbook? Pishaw... I can eyeball the proper 0.017" point gap, as well as the 0.035" 44FF plug gap. A matter of pride.
Well, that's fine and all, but at least the computers can tell you that there is a problem (fault detection), versus a broken wire in a huge cable harness silently failing.
Granted I don't know if you've ever had to write software for control reliable devices, but sometimes the only action is for such a situation is to raise both hands and say "I give up. Fix me I'm broken."
Also people have a knack for blaming the computer and not the sensors or actuators attached to it. Or rather, in your situation it may have been the computer, but typically the ABS light comes on because of a failed sensor (failed as in cable is cut). I see every day people mad at a functioning piece of equipment because it dares to say something back in the form of a fault message about something connected to it.
The ABS system has a test procedure to discover any faults ahead of time, but nobody would ever, ever do it because cars are a culture of just getting in and going, every single time. The correct form of action, also from a liability and absolute safety standpoint, would be to seize up completely after the car had come to a complete stop and engine shut off, if the test failed or fault was detected. Also an impossible thing to expect car drivers to tolerate.
And now back to the topic: I would hope that a main ECM would do a CRC or better check on its entire memory block of critical code, and refuse to operate if even a single solitary bit was different. I have my doubts about that too, and am sure it was overridden, which might lead towards "interesting" outcomes in the coming years.
These are yours, if you want them:
Just email me your mailing address, and I'll get them off to you. (No guarantees on the parts, though.)
Here ya go:
-Phil
In this case it was not me doing the blaming, I had to trust the verdict of my authorized Citroen repair shop. Who knows, maybe they were stinging me for a big repair when a small one would have done.
I have no idea what that might be. What I used to do twice a year or so is find a stretch of empty and usually wet road and jump on the breaks really hard. The ABS all ways worked when I did such a test. If it actually required more attention than that it becomes a useless and expensive feature that actually makes operating the machine correctly harder:) Yep, had it done that I would have been even more miffed. I would have been stranded in the dark, in the rain, in the middle of know where. Had it done that I would say I now have a useless and expensive feature that actually makes operating the machine correctly harder and decreases the possibility that you complete your journey!
All in all the whole ABS thing seems an expensive waste of time so far.
P.S. I have been involved in Full Authority Digital Engine Control for RB211 engines and Primary Flight Controls for various aircraft including the Boeing 777, and a bunch of other mechanical devices. I'm not totally allergic to this kind of control. Even in those carefully built systems I could tell you stories you don't want to hear....
I still have to sort out the problem with my Battlezone game, be it bit rot or just a bad ram chip. Have to move a lot of furniture to get to the back of that game... http://forums.parallax.com/showthread.php/144579-ARRGH!-Battlezone-is-Dead!
Thanks (boy your folks are generous!), but I have found newly manufactured similar chips. They are only a few dollars. And note I can get those old chips from the wrecking yard too, but would rather not use old chips.
I'm thinking about "for sure" reliability being as I drive this truck to out in the middle of the forest where cell phones and CB's do not work. (Not fun to have your truck break down there!)
And speaking of how old chips are or when they were written, due to this bit rot problem, they should have "freshness dates" on them like products in the grocery store!
If anyone else has a less mission-critical app for these chips, let me know, and you can have them.
-Phil
The good news is the eproms and eeproms can be reprogrammed and last almost as long as they did originally. Not sure about the proms. They can usually be reprogrammed but since they last so much longer I don't expect to be around long enough to get an idea of how long the reprogramming will last.
These kinds of behind the scenes stories are the stories I'd actually want to hear, but I'm sure you have NDA's and all that. For shame, because making sometimes comical mistakes is how we all progress. Even if it is an immediate and long lasting setback.
I'm aware of my own mortality, but I'd rather fly on an airplane with a history of past incidents (because there was an immediate need to fix the problem to get it back in service), than something new not put through the rigors of reality.
I suppose this is a case of planned digital obsolescence. The car manufacturers are allowed to discontinue a part long before the copyright runs and out, and then exclude others from producing an after-market replacement that is an exact original. (Buy a new car... no parts available, Sir.)
Many of the EPROMs suffer from a transient jolt. Several years ago, many people were looking for replicated PICs for their stepper motor drivers for CNC machines as these had failure problems and a whole new CNC black box replacement wasn't cheap. I suspect with large inductive motors involve, the problem is more serious.
Once you download the correct data to a good hex file, you have plenty of time to figure out how to create and install a new EPROM.
If you can, the simple solution is a bit for bit copy of the original. But I suspect there will always be an after-market that works around the copyright barrier. The world is full of clever people.
Gadgetman is right, there are alternative later chips.
Last year I repaired my A/C that has a UNL2003 chip that was shot. All I had was the UNL2803 available. So I cut off the two unused pins and soldered it in place. IT worked fine without having to mount a big procurement project to the exact replacement.
BTW, another simple form of failure is to have the moisture environment just corrode the pins right off the IC. That is what happened to my UNL2003... nothing internally wrong.
I assume you make an image off the existing good EPROM and can reburn that into the same or similar chip, and it's likely good for another 20 years?