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Thread: 1995 LT1 Flashing Issues EEHack

  1. #16
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    Quote Originally Posted by steveo View Post
    i'd say it would have to be a decent amount of noise to cause issues, the ecm does have some half-decent filtering of its own.

    i developed eehack from start to finish with a crappy switching 1 amp wall wart (i think it used to power a cordless telephone or something). i wouldn't doubt if it had a single electrolytic cap with hot glue on it inside. for a lot of the time the wires were just twisted and taped together too. NEVER had an issue, and i reflashed that particular ECM many hundreds of times.

    its usually when you put these things in cars with 20+ year old wiring that you have issues.. and it's not good wiring at all.. GM used the thinnest gauge possible.

    another possibility is your ECM's VPP circuity is shot. this might be the first time it's ever been used. these are really old ECMs and were never intended for this length of service.
    probably i need to review the wirings this night and test with my workstation laptop to see if changes anything...
    i just tested with the CAP on the circuit and same result...
    i´m also trying to see if i can get another ECM with this same number to do some tests but its kind of hard right now here in town...
    do you know what pin would be "responsible" for the VPP? probably i will have to open this up to see if i can find anything visually damage.

  2. #17
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    Quote Originally Posted by steveo View Post
    don't suppose you have an oscilloscope, do you?
    no. i dont have one. but i´m planning to "build" one of those simple cables that we can use the sound card on the laptop to see if i can play with it...
    Dont know if it will be any good or not or if it would accualty help me on this...
    I might give it a shot latter tonight.
    i´m kind of busy right now with my actual work so i need to do these things at night...
    i will keep you posted on the results...
    Thanks for the help guys...

  3. #18
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    To rule out all possible issues with your current setup, and confirm the pcm is good, get a good battery and wire straight to the pcm

    d1,a2-ground
    b15,b31 -B+
    d3,b30- Ign switch
    d30 - aldl line

    Run the laptop on a battery supply and wait at least 10-15 seconds with ign on before starting the flash process.

    Are you flashing both sides or single side only. Try to flash both sides.

  4. #19
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    I'm curious what you guys figure out since he's on the bench. I've seen some of those china usb boards have problems :(

    To the OP, the blue board you are using and talked about earlier...where did that come from? I think I wanna check that out. Can you take a close up pic? I tried to blow up the one posted but it got too blurry.
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  5. #20
    LT1 specialist steveo's Avatar
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    Quote Originally Posted by kur4o View Post
    Are you flashing both sides or single side only. Try to flash both sides.
    i swear i fixed that bug

  6. #21
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    Quote Originally Posted by kur4o View Post
    To rule out all possible issues with your current setup, and confirm the pcm is good, get a good battery and wire straight to the pcm

    d1,a2-ground
    b15,b31 -B+
    d3,b30- Ign switch
    d30 - aldl line

    Run the laptop on a battery supply and wait at least 10-15 seconds with ign on before starting the flash process.

    Are you flashing both sides or single side only. Try to flash both sides.
    im working with the laptop battery supply all the time for this.
    i will try what you mention about the 10-15s time before flash. (i think i already made something like this - waiting time).
    About flashing one or both side, honestly i´m not sure. but i think i see some message about being both sides...

  7. #22
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    Quote Originally Posted by In-Tech View Post
    I'm curious what you guys figure out since he's on the bench. I've seen some of those china usb boards have problems :(

    To the OP, the blue board you are using and talked about earlier...where did that come from? I think I wanna check that out. Can you take a close up pic? I tried to blow up the one posted but it got too blurry.
    I bought that here in Mexico. I use it to try and read/connect some ECM/ECU and other modules on the bench for tests and programming (when its possible).
    I will take some good pictures of the board on both sides and will share it. No problem... I just need a bit more time to be on my "work room" and do all these tests on this ECM...

  8. #23
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    Quote Originally Posted by In-Tech View Post
    I'm curious what you guys figure out since he's on the bench. I've seen some of those china usb boards have problems :(
    Based on the pic these are the best batch of china crap so far. Never had an issue with that ones.


    The one time only I got the vpp error was when the car battery started to die while was doing some prolonged hack job, so it is really weird he got one. The vpp check could be some current check or voltage check and have narrow range so higher than needed voltage can also gives the error.

  9. #24
    LT1 specialist steveo's Avatar
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    the delay before flashing has nothing to do with it, the ecm would refuse to unlock. if you're getting an error during the VPP stage that means we're already way past that point. once the kernel is loaded that timer or any gm security crap is literally out of the loop.

  10. #25
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    Quote Originally Posted by steveo View Post
    the delay before flashing has nothing to do with it, the ecm would refuse to unlock. if you're getting an error during the VPP stage that means we're already way past that point. once the kernel is loaded that timer or any gm security crap is literally out of the loop.
    tested again yesterday and no luck...
    tested with a battery, and got no connection.
    tested with my power supply and tried several times with differente voltage values, and still no luck...
    i´m starting to think that this might be an ECM issue, but since i cant get another OBD1 ECM i´m not sure.

    Dumb question: can we change/modify an OBD2 ECM to became an OBD1?

  11. #26
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    tested with a battery, and got no connection.
    You need to investigate this further. Might be the wiring messing the comms.

    Can you make a verbose log and post it here. Does the pcm has service number?

    What version of eehack you are trying to flash with.

  12. #27
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    Not possible, no. The circuitry is different.
    1990 Corvette (Manual)
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  13. #28
    LT1 specialist steveo's Avatar
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    you have wiring issues for sure, there's no sane reason it would connect with a power supply but not a battery. i recently spent hours of time trying to talk someone through why 'eehack wouldn't work even though he's checked everything' and eventually found his serial data wire was no good.

    ecm needs clean power and ground. interface needs rx/tx connected together and ground.

    that's all it needs

  14. #29
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    Quote Originally Posted by steveo View Post
    you have wiring issues for sure, there's no sane reason it would connect with a power supply but not a battery. i recently spent hours of time trying to talk someone through why 'eehack wouldn't work even though he's checked everything' and eventually found his serial data wire was no good.

    ecm needs clean power and ground. interface needs rx/tx connected together and ground.

    that's all it needs
    Ok. I will check all again and probably will be making some new cables for the connections and will let you guys know...

  15. #30
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    Quote Originally Posted by steveo View Post
    you have wiring issues for sure, there's no sane reason it would connect with a power supply but not a battery. i recently spent hours of time trying to talk someone through why 'eehack wouldn't work even though he's checked everything' and eventually found his serial data wire was no good.

    ecm needs clean power and ground. interface needs rx/tx connected together and ground.

    that's all it needs
    still cant flash ECM...
    Made new cables, and was able to connect with battery and establish connection in EEHack, but i'm still having same VPP error on this...
    I didnt want to do this, but i might need to open ECM and see if i can find any visual issues...
    Question: could i apply the VPP directly to the PCB on the ECM or is there any way we can Flash the ECM with some direct connections to the PCB?

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