What is EEPROM?

Michael Mobile Technician Clinton, Utah Posted   Latest  

More and more technicians are realizing that the OEMs have been making our life difficult when exchanging modules. My first exposure to this was the Toyota and Lexus vehicles that had ECMs that became boat anchors when you lost the keys. Additionally replacing the ECMs required new modules. Sometime between 1998 and now some clever engineers put together a tool called EZ Flasher. This tool would set the ECU to a virgin state. You would then install the ECU and marry keys to it. This is just like a new one works. This saved customers $1K in the difference of cost. The way one can virginize the ECU is by looking for the IC900 EEPROM. Once found you just set the clip on the EEPROM, select the vehicle and push the button. It is all a very simple process. Nowadays there are tools like the Auto Pro Pad and iM608 that also can address the Toyota issue.

EEPROM today refers to data that identifies the ECU to the vehicle. This is primarily VIN and Immobilizer Data. For many of us the object is not to change the MAPs (Calibration Data) Our objective is to make a second hand part work like the original. The best situation is one where the entire ECU can be copied then pasted to the donor. Then it is truly plug and play. No OEM software required. Sometimes it is referring to repairing an ECU at board level. An example would be replacing coil drivers in a Ford Escape ECU. Any work where you have to open up the ECU could be regarded as EEPROM work.

diag​.​net/file/f6aith73m…

As ones ability increases it becomes time to try new things. Like taking the original and donor Toyota ECUs and cloning the original to the donor. What this does is provide a way for one to switch between ECUs when testing. It does not burn the original and the immobilizer does not know the difference. When dealing with EEPROMs there are different ways to read and write them. Some can be read "in circuit" and some have to be removed from the board and soldered to a test board. If it can be done in circuit then you clean the legs of the EEPROM then fasten a clip to it to read. Due to system clocks going active, EEPROMs at times have to be removed or the crystal disabled. I have yet to have much luck disabling the crystal. Remove EEPROM with hot air workstation. Then solder to test board. The data can be read and stored on your PC. The EEPROM can then be resoldered to the ECU mainboard. Repeat process with donor but program EEPROM with stored data.

More and more we are finding that many modules use an EEPROM to store VIN and Immobilizer data. There are private forums dedicated to discovering the EEPROMs. The modules can then either be virginized or cloned. Virginize if you plan on using OEM software to program. Clone if you want a plug and play module. Why would one go to the hassle? The reason is OEMs like GM,Ford, Chrysler, BMW, VW/Audi, Jaguar, Land Rover, Toyota/Lexus, Mercedes and others design parts that are one time use. They are not programmable with OEM tools. The official reasons for this are to prevent chop shops from selling the parts and to limit liability. Like everything else we ask why, follow the money. In order to use second hand parts, you have to be creative.

As reverse engineering has become more astute, the OEMs have become more aggressive in protecting their assets. The OEMs have begun moving away from using a separate EEPROM and have chosen MCUs (Microprocessors) with multiple memory locations capable of caching data. What this presents is a front door that you have to get through before obtaining the data. You knock, and the MCU asks you a question in the form of HEX code, Ox67 (made up data) Your tool will answer, Ox75 Ox99 (also made up) The MCU will either reject your request or let you in. Some handshakes are many bits of data. Some are static and common. Others are specific to the PCM itself. By using this SEED / KEY process the OEMs keep you out of the MAP and other sections of the PCM. This in turn keeps you from programming your PCM with higher horsepower. Companies like Alienware have cracked many of the keys. Mainly the European and Asian variants. Some ECUs you can read out all memory locations, some selected locations and some MAPs only.

Knowing what you are getting into becomes interesting. Bosch has multiple versions of Engine ECUs. All of them have a different method of cloning or getting to work with a different vehicle. BMW for instance uses an ISN code. You have to first downgrade the immobilizer, then read the ISN. The ISN then needs to be programmed to the DME (ECU). This takes special software. I have a binder I keep on every ECU I do. I write notes on each ECU. That way if I get a second opportunity on the same ECU, I can review the process. When I get one that I have to take the walk of shame back to the shop, I make sure I keep up to date on each tools progress. If there is not a solution, I respectfully decline the job.

Bosch MED 17 ECUs can be copied but once done will not work. This is because as the data is copied to the ECU it is encrypted and changed. It takes special software to massage the EEPROM data based on EEPROM and Flash data from the donor and the original PCM. MED 17 variants are very popular in Ag equipment and European vehicles. Even some domestic vehicles use this ECU.

One can start with just a soldering iron, hot air workstation and a chip programmer. Similar to using J2534, you will find that there are huge holes to fill. Soon the $500 investment becomes a gateway to bigger and bigger expenses. On a positive note, if you get into it, your job becomes much more fun. You are able to do things you never expected. You can make otherwise worthless parts a new life in a new car. Kind of like a liver transplant.

+30
Interesting
Helpful
Thanks
Craig Technical Support Specialist
Chicago, Illinois
Craig Default
 

Michael, excellent information, I have done some board level repairs in the past, damaged drivers, path repair, and cold solder rework. Never thought about plucking an eeprom off the board thought. I am going to have to remember this post, another option to keep an older vehicle going a little longer. Thanks Craig

0 Default Ð Bounty Awarded
Jj Technician
Quincy, Massachusetts
Jj Default
 

This is great, Michael. Would a trip to a junk yard for some cheap used modules be a good idea for someone interested in getting their feet wet in this type of work? What other modules typically store data using EEPROM, clusters? Body control? Sorry to hit you with what I'm sure are simple questions for you, but this stuff is fascinating and doesn't seem like it's discussed all that often.

+1 Default Ð Bounty Awarded
Michael Mobile Technician
Clinton, Utah
Michael Default
 

JJ, I think it would be a good exercise to grab some of those modules and experiment with them. As modules become obsolete we are going to either have to scrap perfectly good vehicles or learn how to have modules repaired on a board level. Back in the day television and radio repair was a job people made money doing. Electronics became throw away as imports and cheap production became the…

+1 Default Ð Bounty Awarded
Bill Owner/Technician
Jackson, Michigan
Bill Default
 

Michael I personally find this area of automotive repair very interesting! Thank you so much for sharing and bringing to light what must have been told is not possible... I currently do alot of programming and electrical work but nothing like this. How to get started? Aquire or purchase a pile of used ecms?

0 Default Ð Bounty Awarded
Michael Mobile Technician
Clinton, Utah
Michael Default
   

Bill, As mentioned in earlier post, I am working on a class. My objective would be to provide education so the path for others will be smoother. The goal would be to give enough information that each student could either break the bank and go for the Gold or choose a more thrifty path to specialize. The class would have lecture time then hands on work. Everyone can bring their own project and…

+4 Default Ð Bounty Awarded
Thanks
Dmitriy Analyst
Toronto, Ontario
Dmitriy Default
 

Lots of practical and useful info. However, lines like these: “EEPROM today refers to data that identifies the ECU to the vehicle.” ”Any work where you have to open up the ECU could be regarded as EEPROM work.” will make Electrical and Electronics Engineers groan: diag​.​net/file/f3pkz0q95… ​

0 Default Ð Bounty Awarded
Michael Mobile Technician
Clinton, Utah
Michael Default
 

Hi Dmitriy, You got me. The article was not meant to be a technical paper. Obviously an EEPROM is a specific electronic device. Culturally it is common for us to use terms that are not technically true but are commonly accepted. We refer to all adhesive bandages as Band Aids. Growing up we called denim jeans Levis even though many companies made jeans with denim. Sodas are commonly referred to…

+4 Default Ð Bounty Awarded
Agree
Dmitriy Analyst
Toronto, Ontario
Dmitriy Default
 

Michael, I see your point, and I do not have a horse in this race. What I wrote was more to underscore the language barrier between the two groups: a group called Electrical Engineers comes up with (carefully thought out) terminology and standards. Another group, "EEPROM techs", appropriates the terminology, but changes the meaning as they like. Why would the first group even want to listen to…

+3 Default Ð Bounty Awarded
Chris Diagnostician
Lebanon, Ohio
Chris Default
   

You know I'm not much on spreading information like this content. I suppose there is no stopping it but what I will say is; The electronics engineers can and do implement EEPROM chips that will erase themselves if attempting to read. Apple devices were the first to implement this feature to prevent independent repair facilities from performing repairs. What I do know is if there is a buck to…

0 Default Ð Bounty Awarded
Michael Mobile Technician
Clinton, Utah
Michael Default
 

Hi Chris, I respect your view on this. Having a healthy debate on issues is an important part of society. I don't think I can convince anyone of my way of thinking. Maybe at least we can gain an understanding for each other's views. I think culturally we come from a different place. Out here in the West we don't like folks telling us we can't do something. We just want to live our lives without…

+9 Default Ð Bounty Awarded
Agree
Steven Instructor
Cumming, Georgia
Steven Default
 

Mike, I was with GM when we started "reprogramming" the EEPROMs on GEO's Storms in the very early 90's. In the general North American aftermarket, I believe this was a first for ECUs. We sent new calibration files within a cartridge for the Tech1/1A and later the Mastertech 3100. So, when you say "EEPROM" obviously, I recollect different specific use cases from a different time. I especially…

0 Default Ð Bounty Awarded
Chris Diagnostician
Lebanon, Ohio
Chris Default
 

It has nothing to do with saving a customer $, using salvage parts, working more greener, or giving yourself an "attaboy" because you were told you couldnt. By this same standard the toyota eeprom job you spoke about has an average going rate in my town of 200.00 bucks. And that's the guy the toyota dealer calls because I refuse to work for cheap when I've invested so much in my career. 200…

-4 Default Ð Bounty Awarded
Disagree
Michael Mobile Technician
Clinton, Utah
Michael Default
 

Chris, As an answer to who my trainer is, I am self taught. When one spends 2 to 3 hours every evening studying automotive electronics, some of it actually sticks. When troubles arise, I reach out to friends on the forums for suggestions. We all contribute as well as glean information. Some of the best sources are also on this forum. I have spent hundreds of hours of research and thousands of…

+5 Default Ð Bounty Awarded
Agree
Helpful
Chris Diagnostician
Lebanon, Ohio
Chris Default
 

It's a pandoras box that can't be closed. It's a bell that can't be un-rang. Look no further than keycode and nastf. That's a pandoras box that was kicked open and you see drastic measure's being taking to curb the effects. Another is free scans from parts stores. Parts people couldnt resist public pressure for clearing codes so now welcome the secure gateway module. Pay no attention to the…

-7 Default Ð Bounty Awarded
Disagree
Bob Owner/Technician
East Longmeadow, Massachusetts
Bob Default
 

Here's my view after zooming out and looking at the big picture. Humans are intuitively curious and driven to explore and discover the unknown. That's why the human race has survived and thrived and started to venture out into the Cosmos. If there is a mountain in front of us, we climb it. It's just what we do. The whole eeprom industry has sprung up for many of the reasons Mike has already…

+11 Default Ð Bounty Awarded
Agree
Thanks
Tim Mechanic
Blytheville, Arkansas
Tim Default
 

True, I could research on my own (and do), and purchase several tools and junkyard computers to perform experiments with and spend countless hours and untold dollars trying to figure it out, OR, I could find someone who has done all that (like Michael), pay him or her for their hard-earned knowledge and time, potentially avoid making bad equipment purchases and fast-track my abilities to start…

+3 Default Ð Bounty Awarded
Agree
Dennis Owner/Technician
Plymouth, Michigan
Dennis Default
 

Tim i have to agree with you​.​We all know we can research or read a book or go to trade school or college for our profession​.​We also know there is no replacement for experience in this field.I think taking a class put on by Michael would put you ahead of the game experience wise because your going to learn all the mistakes he made without committing them yourself.

+2 Default Ð Bounty Awarded
Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
 

I really like that line "Being able to repair vehicles without the permission of the OEM is part of that attitude." This would completely derail the thread if discussed here, but I wanted to say to YOU that I am of the belief that when I buy a car I should legally own ALL of it. It's not the OEM's business anymore if I wanna take it apart and mess with the software, etc.. (note: I'm not…

+6 Default Ð Bounty Awarded
Agree
Kansas Owner/Technician
Chico, California
Kansas Default
 

Yes. Information wants to be free. (Wikipedia has an interesting article by that title.) With all respect for Chris Jacob's argument above, the root of the argument for keeping private the processes you describe seems to be that it protects business interests of one class (those with certain information and capabilities) from erosion by the class of have-nots (ie everybody else), professional or…

+7 Default Ð Bounty Awarded
Agree
Rudy Technician
Montebello, California
Rudy Default
   

Chris Jacob- What is the difference between what Mike is trying to spread,compared to what all of the ECU and Module" rebuilders" on the market are already doing?

+1 Default Ð Bounty Awarded
Tim Mechanic
Blytheville, Arkansas
Tim Default
   

I have been more and more interested in learning electronics repair on cars lately. I would be greatly interested in taking a class from you on this subject. Thanks and please keep it up! By the way, I don't have Facebook for various reasons, so I can't reply to that post, but I would still be interested in the class. Thank you.

+1 Default Ð Bounty Awarded
Craig Technical Support Specialist
Chicago, Illinois
Craig Default
 

Tim, check out solder​.​net I have thought about taking a class here myself. Craig

+1 Default Ð Bounty Awarded
Tim Mechanic
Blytheville, Arkansas
Tim Default
 

Will do. Thanks for the tip!

0 Default Ð Bounty Awarded
Rick Technical Support Specialist
Saint Charles, Missouri
Rick Default
 

Mike, Keep up the outstanding work! We really appreciate your experience and knowledge you share with us. You have and continue to pay your dues in our complex field. We need mentors like you to keep us informed and motivated. Thank You

+5 Default Ð Bounty Awarded
Agree