Hacking/tuning the jeep ecm

[1project2many]

De-solder the EPROM, figure out the offset for the chip being used, read and upload the chips contents to a file on the computer.&

Do the DSM ecu's EPROMs contain executable code? Early GM ecm's placed code on a separate PROM while the removeable EPROM contained primarily calibration data which made things much tougher in the beginning.

Cracking GM code was done as a project at Ohio State University way back when by genius type computer geeks who knew microprocessor languages and took a team and years to get it done... luckily all the rest of GM code was similar so we have hacks for most...

I uderstand the point behind this but I want to set this straight. The only connection to OSU was that the DIY_EFI mailing list was hosted there when enough like minded guys were on the list to get the project started. Most of the guys in the project were not computer geeks who knew microprocessor language. And for all intents and purposes, if the effort resembled a team it was only very loosely so. There were a couple of guys who had some really kewl skills and had done exceptional things working out their own disassemblies. There were some engineers and electronics techs and few guys who had experience with network administration. But there were also plenty of guys who were into cars and had a little advanced skill with automotive systems and believed they could get the GM code figured out. We kludged around in the beginning working out data locations and functions for a very limited amount of stuff. Every now and then someone would find a tidbit or a piece of software that gave a good clue. But the real advancements came when "Ecmguy" decided to reward the efforts being made by releasing a few of his hacs to the public. Without that, the entire effort would probably have fizzled. After that, more and more previously unknown data started coming to light, most of it from outside the group that started the project. What's important is this:

You didn't have to be a genius to make tuning a possibility, but you had to be willing to put in effort and it did require some outside help.

If you could learn how an engine worked chances were you could learn enough to work with code.

You had to pay attention to detail and you had to be veeery patient. Many hours can be burned up with very little apparent progress.

There are some quality hacs around from unexpected sources:

An Avionics tech for a DOD facility. This guy told me he made it a point to spend 20 - 30 hrs per week working on disassembly. He had great access to Motorola documentation, much of which described example circuits and code which exactly matched GM circuits and code.

A Surgeon who taught himself Motorola machine opcodes and used previously existing hacs to do a few uncommon masks such as a turbocharged lotus and a ZR1. He found it relaxing.

A dentist and a network admin who spent a bunch of time working out code for the 7749 / $58. I believe they were the first to release a 3 bar calibration for the SyTy world.

An Apple computer guru. He liked Fieros and got curious abuut what was in his car's ecm.

An engineering student who wrote some interesting papers because he was curious about how the ECM code actually worked.

It would be unfair to believe you couldn't do this because it takes some god-like ability or talent. But it does take time, dedication, help, and desire.

/soapbox

[rts91tsi]

Do the DSM ecu's EPROMs contain executable code? Early GM ecm's placed code on a separate PROM while the removeable EPROM contained primarily calibration data which made things much tougher in the beginning.

Yeah, the DSM's EPROM contains executable code.