Trying to find the EEPROM in a 98 LS1 PCM

EPROM EEPROM SRAM NVRAM Flash chips, reading/writing hardware and software
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Re: Trying to find the EEPROM in a 98 LS1 PCM

Postby Gampy » Thu May 26, 2022 11:05 am

I wouldn't be to optimistic with that either ... In fact I wouldn't waste my time.

I would BDM write a known good, proper and complete GM original file.
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Re: Trying to find the EEPROM in a 98 LS1 PCM

Postby kojab » Thu May 26, 2022 11:08 am

I would like to look at a bin file that does have data in 4000 or 6000. If the data in one of these blocks is similar to P01/P59 its possible I might have the answer for you.

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Re: Trying to find the EEPROM in a 98 LS1 PCM

Postby jamesried » Thu May 26, 2022 11:40 am

Here's the file with data there, it is not similar IMO.
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Re: Trying to find the EEPROM in a 98 LS1 PCM

Postby jamesried » Thu May 26, 2022 11:42 am

Gampy wrote:I wouldn't be to optimistic with that either ... In fact I wouldn't waste my time.

I would BDM write a known good, proper and complete GM original file.


This is a file that worked 100% good via same BDM recovery, already back in the car and driving around. I'll read another good PCM I have and see if it has anything in that area, I wrote entire the tune pulled from the "bad" one via HPTuners to it and it is still fine. So HPT maybe skips that section or it's not relevant and just part of the normal calibration/OS/etc.

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Re: Trying to find the EEPROM in a 98 LS1 PCM

Postby kojab » Thu May 26, 2022 11:53 am

jamesried wrote:Here's the file with data there, it is not similar IMO.


To me the 4000 block looks to be very badly corrupted.

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Re: Trying to find the EEPROM in a 98 LS1 PCM

Postby antus » Thu May 26, 2022 12:02 pm

its true, GM use 'eeprom emulation' which is the parameter block partition on the main flash. There is no external eeprom, even if its sometimes referred to. Some later (eg P10/P12/p12b from about 05-07) have a different 512 byte eeprom space on the CPU, but not the generations of hardware we are talking about here. If the code is referring to corrupted eeprom, its referring to the active paramater block on the main flash (there are two, when its updated its written to the other partition and erased from the current one, so the active one alternates each update). being a 98 it is possible the flash chip is good for less wear cycles than newer pcms and it may be starting to fail and corrupt that segment. If the flash chip is physically starting to fail like that you'll want to get a good bin with good parameter block data from either this pcm if you have one from when it was working or from another one and replace the entire flash chip for chip level repairs, then update the VIN. I agree the 4000 block is damaged in this bin, there is no vin, no valid seed/key and the data structure looks damaged and incorrect, although I admit I havnt done a deep dive on a 98 pcm, I am working from what I know of 99+.
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Re: Trying to find the EEPROM in a 98 LS1 PCM

Postby jamesried » Thu May 26, 2022 12:17 pm

kojab wrote:
jamesried wrote:Here's the file with data there, it is not similar IMO.


To me the 4000 block looks to be very badly corrupted.


That's a 100% perfectly fine working file that checksums great. Flashed with BDM and no issues.

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Re: Trying to find the EEPROM in a 98 LS1 PCM

Postby jamesried » Thu May 26, 2022 12:19 pm

antus wrote:its true, GM use 'eeprom emulation' which is the parameter block partition on the main flash. There is no external eeprom, even if its sometimes referred to. Some later (eg P10/P12/p12b from about 05-07) have a different 512 byte eeprom space on the CPU, but not the generations of hardware we are talking about here. If the code is referring to corrupted eeprom, its referring to the active paramater block on the main flash (there are two, when its updated its written to the other partition and erased from the current one, so the active one alternates each update). being a 98 it is possible the flash chip is good for less wear cycles than newer pcms and it may be starting to fail and corrupt that segment. If the flash chip is physically starting to fail like that you'll want to get a good bin with good parameter block data from either this pcm if you have one from when it was working or from another one and replace the entire flash chip for chip level repairs, then update the VIN. I agree the 4000 block is damaged in this bin, there is no vin, no valid seed/key and the data structure looks damaged and incorrect, although I admit I havnt done a deep dive on a 98 pcm, I am working from what I know of 99+.


That is just how these work, that data is not in the flash, even doing a full read and write with a BDM it does not touch the vin, serial number, seed, key, etc. It's in another chip somewhere else. It's alluded to by multiple people in other forums 10+ years ago when these were more common to be messed with. Those people unfortunately aren't responding to PMs lol

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Re: Trying to find the EEPROM in a 98 LS1 PCM

Postby Tazzi » Thu May 26, 2022 12:24 pm

jamesried wrote:That is just how these work, that data is not in the flash, even doing a full read and write with a BDM it does not touch the vin, serial number, seed, key, etc. It's in another chip somewhere else. It's alluded to by multiple people in other forums 10+ years ago when these were more common to be messed with. Those people unfortunately aren't responding to PMs lol


If this is a P01 style PCM then the VIN,Serial,Seed,Key ect is all part of the parameter block.

If that block is corrupted or wiped, then you will get funny characters when loading up in software such as hptuners, lsdroid, pcmhammer ect.

*Edit
Appears this is not a standard P01.
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Re: Trying to find the EEPROM in a 98 LS1 PCM

Postby jamesried » Thu May 26, 2022 12:30 pm

Tazzi wrote:
jamesried wrote:That is just how these work, that data is not in the flash, even doing a full read and write with a BDM it does not touch the vin, serial number, seed, key, etc. It's in another chip somewhere else. It's alluded to by multiple people in other forums 10+ years ago when these were more common to be messed with. Those people unfortunately aren't responding to PMs lol


If this is a P01 style PCM then the VIN,Serial,Seed,Key ect is all part of the parameter block.

If that block is corrupted or wiped, then you will get funny characters when loading up in software such as hptuners, lsdroid, pcmhammer ect

*Edit
Appears this is not a standard P01.


Yeah this is the very first ls1 pcm used in 97-98 vehicles and the dbw 24x coil near plug 7.4 big blocks in big trucks. Similar but very different animal and very hot garbage temperamental.
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