Jeep SBEC PCM tuning (91-95)

[a_kelley]

Knocked out a schematic and a board layout. Kicad has a slight learning curve compared to what I was used to using back in 2004. (Don't remember if it was pads or eagle or what). Will try to fab a few when I get some spare time. SMD would be the way to go with home made boards. I've got a drill press though and some tricks. I can do toner transfer with resolution down to about .006 tracks (was a .5mm pitch package break out board.. eek) so through hole is no issue.

 

[sev80]

Whoa. I've been away with a new baby and job, and for some reason the forum didnt notify me there's new posts. Glad to see Andrew's work is progessing and there's interest!

 

[sleach0]

Had to rewire one of the chips on board (cut two traces & three green wires), remove the old eprom and install my new eeprom. I can post how to do it if there's interest. This particular picture is of the test board I did first, I wouldn't remove that much of the potting if I were planning to reseal it. I did that just to see what else was on the board and be able to poke at it.

View attachment 257843

This is a 356 SBEC from a 94 I believe. Identified most of the tables in the code and about half of the code.

I haven't torn into my PCM yet. Had a question about what you had to wire on the board to flash the module in PCM. This appears to only apply to the non flash pcms. From the picture above it looks like you ran a wire from somewhere to the WE pin on the AT28C256. It looks like you took the #4 output of the 74HC, which appears to go to the CE pin on the EEPROM and tie it into the 2A input on the 74HC.

I think one of the traces you cut was to the WE on the 28C256 as holding this high inhibits writing. It doesn't appear that there is anything hooked to the 2Y output so if 2A is hooked to the PCM you can control the WE pin on the 28C256 with it.

Still not sure what you are controlling OE with although that has to be tied to the 68HC in order to read so that is probably already done.

To read or write you are putting the 68HC11 into bootstrap mode by applying 12V to the SCI Rx line at key up. You then load in your bootstrap program in through the SCI bus to read or write. If you are writing to the EEPROM then you are reading off of the SCI bus, storing that in RAM, toggling the EEPROM for write, and then writing?

It looks like the programming voltage is only for if you have a flashable PCM?

I've read through this about a dozen times now. Thanks for doing all of this.

 

[a_kelley]

I haven't torn into my PCM yet. Had a question about what you had to wire on the board to flash the module in PCM. This appears to only apply to the non flash pcms. From the picture above it looks like you ran a wire from somewhere to the WE pin on the AT28C256. It looks like you took the #4 output of the 74HC, which appears to go to the CE pin on the EEPROM and tie it into the 2A input on the 74HC.

I think one of the traces you cut was to the WE on the 28C256 as holding this high inhibits writing. It doesn't appear that there is anything hooked to the 2Y output so if 2A is hooked to the PCM you can control the WE pin on the 28C256 with it.

Still not sure what you are controlling OE with although that has to be tied to the 68HC in order to read so that is probably already done.

To read or write you are putting the 68HC11 into bootstrap mode by applying 12V to the SCI Rx line at key up. You then load in your bootstrap program in through the SCI bus to read or write. If you are writing to the EEPROM then you are reading off of the SCI bus, storing that in RAM, toggling the EEPROM for write, and then writing?

It looks like the programming voltage is only for if you have a flashable PCM?

I've read through this about a dozen times now. Thanks for doing all of this.

More or less. I'd need to look at my notes to verify any thing, it's been awhile and on the way back burner. Considering making it open source and open hardware.. though open source != Free. You can dump any ecm. You can only write modified eeprom (any using the atmel eeprom) or factory ST flash units or factory Toshiba rechipped with ST or equivalent. Though if I could get my hands on the Toshiba spec that could be added.

 

[Lamberto]

Hello everyone,
I read the whole topic of the forum, you all did a great job and useful for all owners of SBM PCMs.
I write from Italy, where unfortunately American engines are not widespread. I have two jeeps, a zj 5.2 '96 and a tj 4.0. Recently the tj has burnt and I am rebuilding it.
I'm following this topic because I bought an engine of a ZJ '93 to be mounted on the TJ and I would like to reprogram the PCM removing the security of the SAM module (which I don't have).
now I have disassembled the original eprom and I have put a soket, I am trying to understand how to connect the WE pin of the ATMEL memory.
I thought of connecting it as the following image, what do you think?



Can I remap with MP Tune with this change? Are you familiar with other remap the PCM software? if it helps, I read the original eprom .bin(ZJ 5.2 '93) with an eeprom programmer.
Thanks a lot for any information.

 

[a_kelley]

Pm me and I'll discuss further. I've much going on in my life and this kind of got back burner. I still have everything and would like to produce the interface and open source the editor so that way it can become what it ought to be.

 

[Lamberto]

I would be very happy to help you, I am an electronic engineer specialized in PCB routing.
If I can help you with anything, don't hesitate to contact me
Thanks so much

 

[Rovers]

Pm me and I'll discuss further. I've much going on in my life and this kind of got back burner. I still have everything and would like to produce the interface and open source the editor so that way it can become what it ought to be.

Sendning you an pm

 

[ramon]

lot of thanks to all in the post a lot of job right here anybody knows where can i find mp tune?

 

[a_kelley]

Hello everyone,
I read the whole topic of the forum, you all did a great job and useful for all owners of SBM PCMs.
I write from Italy, where unfortunately American engines are not widespread. I have two jeeps, a zj 5.2 '96 and a tj 4.0. Recently the tj has burnt and I am rebuilding it.
I'm following this topic because I bought an engine of a ZJ '93 to be mounted on the TJ and I would like to reprogram the PCM removing the security of the SAM module (which I don't have).
now I have disassembled the original eprom and I have put a soket, I am trying to understand how to connect the WE pin of the ATMEL memory.
I thought of connecting it as the following image, what do you think?
View attachment 312649


Can I remap with MP Tune with this change? Are you familiar with other remap the PCM software? if it helps, I read the original eprom .bin(ZJ 5.2 '93) with an eeprom programmer.
Thanks a lot for any information.

you can do that, but if you look back towards the first few pages, you can see where I green wired a atmel in place. However, the catch is that the board must have an address latch built in. The 87c257 had it integrated into the eprom chip. The boost button board can be used if your ECU used the 87c257. There are several board revisions and not necessarily any really easy way to tell without digging in the potting. I've got one modified with an atmel chip and another with a flash chip and a stock flashable unit, and a protype interface. Pm if interested and we'll look into what I've got invested in them and shipping.

 

[DoubleG]

I have a jeep grand cherokee 5.2 94 in which SBEC II got burned. I bought another similar one, but it is locked car starts up only for a moment how to unlock this ecu,
i have programmer tl866 which can read 27c256 or this lock is in other memory? thank you for your help

 

[AdamRosas]

Attached is the EPROM from my 92 2.5L Manual YJ with a 56027382 ECU, anybody have the EPROM for a 56028828 ECU?

 

[AdamRosas]

Attached is the EEPROM from a 95 Dodge Ram 1500 Auto with a 56028078 ECU.
The 56028078 seems to have a different CPU, SC415126VFN a suspected
MC68HC11E1, is missing the 4632650 chip and has a Toshiba TC97209P
EEPROM. I attempted to run the 2.5 code on it by padding the reset vector
to 0xFFFF, which didn't work.

 

[AdamRosas]

Another 4 cylinder EEPROM. This one is from a 1995 Jeep Cherokee 2.5L Manual with a 56028842 ECU
after replacing the capacitors I tested the ECU in my 2.5L Jeep Wrangler, ran the engine as well if not
better than the stock ECU.

 

[AdamRosas]

attached is the EEPROM for a 1995 JEEP GRAND CHEROKEE 4.0L AUTOMATIC with a 56028026 ECU
I was able to flash the 4 cylinder code from the 56028842 ECU and test it in my 4 cylinder Jeep YJ

If you don't want to pay $300-$500 for a 4 cylinder ECU, then the much more plentiful and cheaper
ZJ 56028026 ECU cross flashed with the XJ 56028842 and likely the YJ 56028828 4 cylinder code
will save you a few hundred dollars.

 

[roelant]

Oh also I bought a mpscilink. Should be shipping to me sometime soon. Found all the memory locations for the Jeep SBEC to get mpscan to work. I assume Mpscilink will allow me to plug in memory locations so I can datalog with it as well...

Any chance of getting the info on memeory locations from you? Please contact me if you cam roelant@s-nl.net.

 

[Ron]

Any chance of getting the info on memeory locations from you? Please contact me if you cam roelant@s-nl.net.

Looks like the dude you quoted hasnt been on the board in over 7 months

 

[roelant]

Yes that's unfortunate, is there any one who can help me with finding the ram locations for a 4.0 liter sbec of a yj from 92? So i can use mpscan to loo into things? Or even a original.bin file? Help would be appreciated a lot... I am trying to get this old jeep going for a friend, It has a stroker motor that was build 10 years ago, never ran, the project was never finished.. Now i can not get it to run, ignition is way off, fires at 60 degree before tdc. I think the sbec might be upset , maybe bad capacitors. Maybe the wrong sbec for this car, it might have been swapped. I have some other sbec but these are for v8 5.2 Cherokee engines. I might try to socket one of these and put 6 cyl code in it. Would that work?

You guys seem to have gained a lot of knowledge about these sbec's. Hope you can give me some hints..
Greatings from the netherlands...

 

[AdamRosas]

Yes that's unfortunate, is there any one who can help me with finding the ram locations for a 4.0 liter sbec of a yj from 92? So i can use mpscan to loo into things? Or even a original.bin file? Help would be appreciated a lot... I am trying to get this old jeep going for a friend, It has a stroker motor that was build 10 years ago, never ran, the project was never finished.. Now i can not get it to run, ignition is way off, fires at 60 degree before tdc. I think the sbec might be upset , maybe bad capacitors. Maybe the wrong sbec for this car, it might have been swapped. I have some other sbec but these are for v8 5.2 Cherokee engines. I might try to socket one of these and put 6 cyl code in it. Would that work?

You guys seem to have gained a lot of knowledge about these sbec's. Hope you can give me some hints..
Greatings from the netherlands...

I put all the EEPROMs I have collected from these threads in a github repo that can be found at GitHub - AR1972/jeep_2.5L: 91-95 Jeep and Dodge EPROMS. Maybe the file you need is in there, feel free to submit a pull request if you have an EEPROM you wish to share.

 

[AdamRosas]

I found the ECU configuration flags, bit 7 configures the ECU for 4 or 6 cylinder operation,
bit 0 the transmission type. 0x81 = 4 cylinder manual, 0x80 = 4 cylinder auto. Six cylinder
version are set to 0x41 = 6 cylinder manual, 0x40 = 6 cylinder auto. I'm not sure what bit 6
configures the ECU for, I suspect an electric radiator fan, or power steering pressure switch.

I flipped bit 7 in a 6 cylinder ECU and tested it in my 4 cylinder YJ, it idled at 1000-ish RPM, but
ran and drove perfectly otherwise.

 

[roelant]

Thanks for all the info, will look into it!
I have bin files of 56026982 (6 cyl) and P5249545 (8 cyl mopar performance pcm ) . Are you interested in those?
I have ordered new capacitors and hope to get my 6 cyl sbec going again.
Thanks again

 

[AdamRosas]

Thanks for all the info, will look into it!
I have bin files of 56026982 (6 cyl) and P5249545 (8 cyl mopar performance pcm ) . Are you interested in those?
I have ordered new capacitors and hope to get my 6 cyl sbec going again.
Thanks again

Thanks for the files, I looked at the 6 cylinder file there is no code changes from the 56027384 EEPROM and
some small changes to a few tables and 3 single byte changes in the data section. these differences could
be Cherokee vs. Wrangler stuff, or Europe vs. North America stuff, very helpful in ether case.

is this file from an un-tuned ECU? how did you extract it from the ECU, I ask because there seems to be some
values from the internal CPU EEPROM. you could try changing all values in the rage 0x3600 to 0x37FF to
0xFF.

The 8 cylinder file appears to be incomplete I think it is a 64k EEPROM, what year is this ECU? it might
be possible to get the 6 cylinder code running on it, but it will probably be a lot of work. If you could get
a full dump of the EEPROM, I'll take a look at it.

 

[AdamRosas]

Happy Halloween...


I got the 4 and 6 cylinder code running on the 5.2L 8 cylinder ECU, the TI
chip has changed from $6400-$60FF to $400-$4FF address space.

Took the 4 cylinder YJ for a spin this morning, runs and drives normally.

I pushed the changes to my github, if you have one of these 94-95-ish
8 cylinder ECU's, you are now able to build an EEPROM image that will
run a 4 or 6 cylinder engine, the 56028078 pop up on ebay all the time
for well under a hundred bux, they are missing a chip that handles the
cruise control, but still better than spending $500.

 

[AdamRosas]

I got the 95 XJ code running on my 92 JY ECU, same deal as before
TI chip base address is $6000-$60FF for these ECU's. My 92 YJ
runs and drives perfectly. We can now convert any Jeep or Dodge
ECU to run a 4 cylinder Jeep. Scalpers can suck it.

 

[AdamRosas]

After many hours of fiddling, I finally got MPtune to spit out the EEPROM
from my 56028828 1995 Jeep Wrangler 2.5L Manual federal emissions.