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CeC technical information? |
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abzman
AMC Fan Joined: May/09/2020 Location: 48030 Status: Offline Points: 2 |
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I want to believe that the chip with the socket on top is just a pinout adapter and contains no smarts because I've never seen anything like it and wouldn't know where to start in guessing what it is or figuring out how it's hooked up
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FLynes
AMC Apprentice Joined: May/25/2010 Location: Nampa, ID Status: Offline Points: 110 |
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I love reading threads like this, because electronics fascinates me. My father was an electronics engineer at Westinghouse from 1974-1990 and I remember him bringing home these massive HP computers with tiny screens, so he could repair them and run diagnostics. I remember playing Blackjack on one. If you guys are at a standstill with this project, you might want to reach out to a guy on YouTube, who is an electronics guru, named Paul Carlson. His channel is "Mr. Carlson's Lab". He specializes in old tube electronics, but he also has a newer Pontiac Firebird and has done some modifications to its computer system. Reading your journey into discovering what makes the CeC tick definitely makes me appreciate the Prestolite ignition system and Carter YF in my CJ-5, although I will admit that I've been very tempted to take my spare module apart to see the guts. I fully understand about talking to brick walls, because so many people, lead by a self-proclaimed ignition expert on the Jeep Forum, are convinced that the Prestolite ignition is crap but, in reality, much like your O2 sensors, it's a matter of Preventative Maintenance. BTW, my ignition and fuel system is still 100% original and I get between 21-23 MPG highway up here in Idaho, 17-19 MPG in the city. Good luck with your endeavors.
Edited by FLynes - Jul/31/2020 at 1:23pm |
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Fred
1976 CJ-5 <font color=LIME GREEN>Lime Green[/COLOR] 258/T-150 3.54:1 |
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MIPS
AMC Nut Joined: Mar/11/2019 Location: Kamloops, BC Status: Offline Points: 346 |
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Funny enough, Mr. Carlson lives a few hours west of me down on the coast. I drive past his neck of the woods a few times a year. Legend has it AvE is even closer, but nobody knows for sure.
I'm not even sure how you would get in touch with Carlson. Ever since youtube abandoned private messaging years ago I've had no clue how to contact other users. |
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5704nMango
AMC Fan Joined: Jan/11/2021 Location: Palos Heghts Status: Offline Points: 1 |
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Thanks for all your information on the 196,you have given me the confidence to work on mine. I have a 1962 Rambler American that needs work, engine and body. I have a ton of questions I would like to ask you
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ciostko
AMC Fan Joined: Feb/07/2021 Location: Poland Status: Offline Points: 2 |
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Hello,
I'm in the process of writing my Master Thesis. I will be conducting
tests on parts from the inline 6 cylinder 4.0L Jeep engine. I need to
find out what materials each component is made of and whether they have
any anti-wear coatings.
Parts that interest me:
- engine block (especially cylinders / sleeves)
- crankshaft
- pistons
- piston pins
- piston rings
- main and crank bearings
- camshaft
- camshaft cams
- inlet and outlet valves
I don't need the percentages of the individual alloys. I just need
general information about what is there.
I look forward to hearing from you.
Could you be that kind and help me? Or tell me where can I find those
informations? Best regards
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MIPS
AMC Nut Joined: Mar/11/2019 Location: Kamloops, BC Status: Offline Points: 346 |
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I am still working away at this. It has slipped further down the list of things to do but in the last few months I was asked what could cause the stepper motor driver to blow up as it seems it has happened multiple times to multiple people
As I believe I mentioned a few pages back, the stepper motor on the feedback Carter 2bbd is a 2-phase center tapped device that connects directly to the computer. Inside it is driven by a 16-pin DIP made by National Semiconductor but Ford has put their own custom marking on the chip which you will not find in any parts catalog which makes it very hard to determine what the chip really is and made even harder by the possibility it has not been in production for decades. The best you can do is look at the circuit around the chip to see how the circuit is designed. I went back to my computers and came up with this: It isn't a dedicated stepper motor driver chip. (which is a little bit of a relief) Two identical chips are used to drive the stepper motor and the solenoids for the Air Management System, the vacuum control of the Sol-Vac and I think the Idle Speed Relay. They are likely high current drivers. Four data lines come directly from the microprocessor, power goes in, you have grounding and you have the signal outputs. In this case the outputs are not "pulled high" (that is the "off" state is equal to ground) but "pulled low" (the "on" state is equal to ground). The stepper motor and everything else when the computer is powered is also getting battery voltage full-time. It just needs the driver to complete the path to ground and the driver is there in the first place because microcontrollers on their own are pretty lousy at doing this and it typically protects the microcontroller in the event of a fault. Why does this matter? The hint was a sticker inside the carrying case for my ET-501 tester warning that when testing vehicles equipped with secondary air, make sure the solenoids are not shorted BEFORE connecting the tool. If the solenoids are shorted (or more likely, the flywheel diode has failed in a dead short) when you apply power you force battery voltage with no current limiter into the tester and fry it. The same applies to the drivers in the computer. If the solenoids or stepper shorts directly between battery voltage and the signal pin there is probably no protection mechanism in the chip as the windings should of been doing this for you and it blows up as soon as it tries to pull the line to ground. |
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MIPS
AMC Nut Joined: Mar/11/2019 Location: Kamloops, BC Status: Offline Points: 346 |
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I think I did it. The adapter came in and the ROM seemed to dump and verify back to the microcontroller with the same checksum.
I have NOT however verified if it was a *GOOD* dump. The only way to do that is write the binary back to another chip (like the Intel 8749 which is the same chip, but with a window so you can erase and reprogram the ROM using a UV lamp), plug that back into the CeC and run the MCU test on the ET-501 but right now my programmer has enough umpf to read but fails while trying to write. So nobody break out the champagne just yet, if reverse engineering an 80's emission system is something to celebrate. In the meantime I quickly fed it through a code disassembler. The code below is from a 1982 model year Eagle with Canadian emissions. It is untested to confirm if it's actually valid.
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6PakBee
Supporter of TheAMCForum Charter Member Joined: Jul/01/2007 Location: North Dakota Status: Offline Points: 5454 |
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I am no computer guru, far from it. But that code dump looks like assembly language. Move, jump, clear, decrement...... Am I close?
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Roger Gazur
1969 'B' Scheme SC/Rambler 1970 RWB 4-spd Machine 1970 Sonic Silver auto AMX All project cars. Forum Cockroach |
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MIPS
AMC Nut Joined: Mar/11/2019 Location: Kamloops, BC Status: Offline Points: 346 |
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You are correct.
Because at that time in history, space was a major limiting factor in computers, the CEC was programmed entirely in assembly. The ROM, or "firmware" as we call it now takes up an entire 2 kilobytes of space. Prior to being written to the ROM the assembly code is compiled to collapse it down further, remove any code commenting that isn't needed in the final product and brings all the components created in the development environment together into one object. Once it's compiled you cannot get any fancy formatting or code comments back, so a utility like DASMx can de-compile the ROM back to how it was (probably) written but we cannot see anything the programmer might of wanted to point out, like state branches, mode switches or how/when it responds to malfunctions. It's up to someone far more educated in assembly (in this case for the MCS-48) to look at the code and see what it's doing. Between the family reference manual and the programmers reference Intel alone has some 600 pages of documentation. I will admit this is over my head as I am more a hardware person. Edited by MIPS - Aug/20/2023 at 10:56pm |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19612 |
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I don't know how much assembly experience Tom Jennings has, but hopefully he will see this and make some comments... even if it's "over my head too"...
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Frank Swygert
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