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CeC technical information? |
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MIPS
AMC Nut Joined: Mar/11/2019 Location: Kamloops, BC Status: Offline Points: 347 |
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@tomj you are pretty much correct. After spending more time getting used to AMC's part numbering scheme it's becoming apparent that for example a chip that is stamped D9AF-DA and has a suspicious wiring arrangement of a driver can very well be a ULN2074 quad darlington switch, but with a custom silkscreening because a vendor will give you that option once your order quantity goes into the hundreds of thousands or millions of pieces.
Indeed you are correct in that commodity microcontrollers of this era lack virtually any security, mainly due to the unlikely chance at the time a person had both the equipment and the knowledge. 8048's are pretty easy to dump, but the adapters for programmers like my Willem are not cheap, even today. With that in mind, given just how similar the 82 model CeC design is compared to the pictured 87 model MCU, I am going to make a safe assumption that it uses the same microcontroller with an internal mask rom. Also just in case anyone is wondering if me depotting the first computer damaged it, the tester says it's still fine. Don't know how it concludes that but that's peachy in my books. Edited by MIPS - Oct/10/2019 at 9:00pm |
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tomj
AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7555 |
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that's all pretty freakin amazing. that gear is beautiful. thanks for the great work!
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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pacerman
Supporter of TheAMCForum Joined: Jul/03/2007 Location: United States Status: Offline Points: 9060 |
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Just an observation but would not the D9 portion of the that part be correct for a 1979 Ford. Was Ford using the same logic software as AMC or more probably, was AMC using Ford hardware?
OK nevermind. I re-read the thread. Of course the were. Joe
Edited by pacerman - Oct/10/2019 at 9:46pm |
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Happiness is making something out of nothing.
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FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742 |
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Good to see a 1984 and up "Super D" getting dissected.
All this is leading to the eventual goal of dumping the code off that 8049, altering the code for a custom engine tune, and re-writing the altered code to an external PROM. That would be really, really cool and allow Eagle owners to get their engines really tuned well. Modern gasoline does not run like 1980's gasoline, so some of the open loop fuel mixtures need adjusting. I am comforted to see the original code was written in MROM rather than PROM, so it shouldn't deteriorate with age as much as PROM. Edited by FSJunkie - Oct/13/2019 at 5:08am |
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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tomj
AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7555 |
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currently on abebooks.com is this:
Motor 1983-84 American Motors, Chrysler and Ford Vacuum and Wiring Diagram Manual/Professional Service Trade Edition (Motor Chrysler/Eagle/Jeep Ford . Manual Professional Service Trade Edition)$4.35!!! it's Motors, not AMC, but a trade professional book, not hobbiest. If no one else buys it i might even though i have zero interest in 80's cars. |
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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MIPS
AMC Nut Joined: Mar/11/2019 Location: Kamloops, BC Status: Offline Points: 347 |
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So now that I have spent a considerable amount of time over the summer reverse engineering the 82 and 83-87 computers, understanding their theory of open and closed loop operation and constructing my own testing device to compare data the official tool does not show, while I am getting really good at identifying problems it's becoming increasingly clear that the initial goal of a completely new computer to counteract the 80's emissions mandate is probably outside of the scope of my abilities. There are a number of fixed functions that cannot be easily changed without modifying the electronics, thus it no longer becomes a drop-in fix. At the same time there are components the replica MCU's need (such as the harness connector) which are prohibitively expensive (one harness connector for an 82 model year CeC is $230CAD each if ordered in quantities of 10) and not entirely feasable to extract from existing MCU's. At the same time this Eagle has been destroying me for money and I've still been unable to get my hands on an adapter to dump the MCU's code. It's still possible and I really want to do it but I cannot set a timeline anymore.
I'm sorry you guys. I'm dropping the ball on this one. We may very well be stuck with the CeC for now unless someone else wants to take a stab at it. In other news, the manual for the ET-501 tool is now available on the Internet Archive where I can assure you it will be available for far longer than my dropbox. https://archive.org/details/amcet501instructionmanual Edited by MIPS - Dec/15/2019 at 8:26pm |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19689 |
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Great effort though! Systems like this get obsolete and costly (if not impossible) to repair over time. Once it reaches that point you either bite the bullet and keep it 100% original, or you pull it all and forget originality. If it's a driver I'd pull it... unless emission laws in your area require you to keep it. Most countries drop emissions checking after a car is 25+ years old, but some (like Japan, I think) don't. Even California exempts cars made in 1975 or earlier (repealed a 30 year rolling exemption in 2005). 76 and later are qualified for an "abbreviated" smog check IF they are at least 35 model years old, at least 25 model years old with Historical Vehicle license plates, or classified as a special interest vehicle. I wouldn't use the "Nutter Bypass" as that leaves the system hobbled, more of a "limp home" state. It works better than a bunged up emission system, but not like it should. Better to bypass everything with a standard carb and distributor. The CEC distributor can be used, but I prefer to get an older model or a new replacement HEI instead since the timing curve is slightly different. It will run better than using the Nutter Bypass, but it still may not be quite as good as a fully working emissions system, especially since the system adjusts the carb on the fly. Just like a regular carb system it will be in perfect tune only under perfect conditions, or the conditions it was tuned for. The CEC system used an O2 sensor and made minor adjustments, which at least in theory should improve gas mileage and power. Not in large increments, 1-2 mpg, 3-5 hp, maybe up to 7-8 hp. Best to get something like a Sniper TBI and replace it all. Any EFI system should be superior to a factory correct/new CEC system, and worth the money and effort if you really intend to drive it for regular transportation. That's why I put a 4.0L with EFI in my 63 Classic.
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Frank Swygert
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tomj
AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7555 |
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Yeah, MIPS, don't feel bad, you drew out a heck of a lot of information. Knowing when to stop is an advanced skill! It was pretty interesting what you got out of it.
I've often thought of writing closed-loop TBI code or occasionally closed-loop carb. Some equiv. to a 200 cfm 1V carb, 150 hp, with mainly self-tuning for altitude. Something like GM's TBI 2-dimensional RPM vs. mani pressure system, but with a wideband sensor. Knock off all the complicated features. But then I come back to my senses. Thanks for the work and the pics of nifty, obscure AMC gear! |
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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abzman
AMC Fan Joined: May/09/2020 Location: 48030 Status: Offline Points: 2 |
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MIPS,
I'm new to the game when it comes to reverse engineering this system, but I've got some electronics skills that I may be able to help out with. I have a 1984 Eagle currently functioning well, but it also came with a bunch of spares. I have a spare second generation computer you've shown here and may be able to dump the program out of it. Were you able to trace enough of the schematic to determine if that's likely the same processor, just relabeled? I know that connector for the earlier computer is expensive, but what's inside it for terminals, might this be a thing someone could design and have 3d printed (just insert the terminals, or make it a pigtail). I'm also somewhat interested in the code in the processor of the original diagnostic computer. I know you posted the roms of the different modules, but the code in the cpu could be helpful in reverse engineering and building a duplicate of that tester. Since I have the later model computer my connector is just an edge connector so for me making a replacement pcb would not be as much effort. Let me know any way I can help, Evan
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MIPS
AMC Nut Joined: Mar/11/2019 Location: Kamloops, BC Status: Offline Points: 347 |
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I'm fairly certain the Microcontroller in the 83 and later MCU's is still just an MCS-48, judging how the supporting circuitry is so similar the the CeC. The MCS-48 uses an external crystal on pins 2 and 3 whereas the MCS-51 which was its successor puts the crystal inputs on pins 18 and 19.
The diagnostic tool itself also uses an MCS-48. It's located behind the front of the tool and is a UV rewritable variant. Again, I do not have the adapter needed to dump it as well. The larger problem is the removable diagnostic ROM piggybacks a large IC that has no markings (on either side) other than it was manufactured by National Semiconductor. My suspicion is that the MCS-48 in the tool is running as a VFD display controller and the unknown chip is actually the main microcontroller which relies on the Diagnostic ROM to operate. Also don't forget that the harness pinout for your MCU is listed near the back of the ET-501's manual I linked to. Edited: It's funny actually, someone was talking to me about the Super-D last night. I was sent a partial photograph of the MCU from an 87 year Jeep and while it's clear there was a revision at some point the layout is still quite similar. (and STILL uses an MCS-48, because why reinvent the wheel?) I wonder what that soldered jumper is for? Edited by MIPS - May/10/2020 at 2:52pm |
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