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Thread: Flashhack Issue

  1. #1
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    Flashhack Issue

    Hello,
    I originally tried flashing a PCM on a mostly stock 1995 Formula and the voltage was not sufficient. I charged the battery overnight and attempted to reflash the PCM. Now I have no communication with the T-side of the PCM. I have to disconnect the battery and reconnect after every attempt.
    Where do I go from here?

    Thank You

  2. #2
    LT1 specialist steveo's Avatar
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    I originally tried flashing a PCM on a mostly stock 1995 Formula and the voltage was not sufficient.
    did the power become low in the middle of the flash write, or did it simply refuse to write? you need to give a way more detailed story here, what happened, what are the symptoms, and what exactly were the messages in the flashhack log

    Where do I go from here?
    post a log of what happens when you try to flash now

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  4. #4
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    Well, I had success flashing the PCM. I had to keep clicking "write calibration" and I attached a copy of the log file. It stopped a total of three times, I also recorded the process on another device, but did not attach it.

    Could it be the PCM has never been flashed and/or old wiring?

    Thank you for your time..
    Attached Files Attached Files

  5. #5
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    Well, if anything, this just proves how amazingly robust Flashhack is; had you attempted to flash this PCM using TunerCats, you would absolutely have had a brick on your hands.

    Something is really wrong with your serial interface; even more wrong than the one on my '94 Corvette (the cause of which I have yet to determine).

    The problem has nothing to do with the PCM having never been flashed before. That is completely irrelevant. The wiring would be the first suspect. Make sure that the grounds between the PCM and the ALDL connector are solid. Make sure the connections between the ALDL pins on the PCM and the bus connector are also solid. After that...you'll probably need something like an oscilloscope or logic analyzer to try to spot the problem. That's the next step for me as well; try to determine what is making my bus "noisy." But that being said, the noisy bus on my '94 never resulted in failed erases or replies; it only ever resulted in silly things like being unable to reboot the kernel automatically after the process was completed. Yours looks far more serious.

    But while we're on the topic, what are you using to connect your computer to the ALDL connector, precisely?
    1990 Corvette (Manual)
    1994 Corvette (Automatic)
    1995 Corvette (Manual)

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    Kind of off topic but may be relevant for future users. Stevo's awesome stuff only works on win7 or newer. I tried and tried to have it work via the serial port I have on my lappys. It never worked. If I used a keyspan(ftdi) usb to serial, it worked perfect. After much traffic logging it appears to be a windows problem although I was able to use John's(Tunercat) with Win7 and the serial port but the logging showed an incredible amount of retries that I don't normally see. It's like the newer windows stuff doesn't understand the original serial stuff, bleh.
    -Carl

  7. #7
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    I have a homemade cable with the generic OBDII male and a USB with the R232 USB Adapter. I had to trace the pinouts to the corresponding wires on the OBDII connector and then make sure the pinouts were correct for an OBDI Computer using an OBDII style plug.
    Should I purchase another or change my existing cable?

    I was checking the voltage the other day for the reflash, and I checked the voltage across the battery+ junction near the PS reservoir and the voltage really jumps around and does not become steady. Next, I will replace the junction. I wont attempt a reflash, I do not want to brick the PCM.
    I will check and clean the grounds and connections between the ALDL and PCM..
    Last edited by Janson9027; 11-24-2021 at 05:31 PM.

  8. #8
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    If your main battery voltage is jumping around wildly, then yeah, that sounds like your problem. Do check the grounds too, yeah.

    As for your homemade cable, it depends on how the cable was actually made. Which "RS232 USB adapter" specifically are you using? Is it a real FTDI? Or is it something else?
    1990 Corvette (Manual)
    1994 Corvette (Automatic)
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  9. #9
    LT1 specialist steveo's Avatar
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    i use a set of libraries called QT to make my code work with pretty much any operating system (some people even build flashhack and eehack to run natively on macos or linux)

    unfortunately they dropped support for XP years ago

    so yeah windows 7 minimum now

    Quote Originally Posted by In-Tech View Post
    Kind of off topic but may be relevant for future users. Stevo's awesome stuff only works on win7 or newer. I tried and tried to have it work via the serial port I have on my lappys. It never worked. If I used a keyspan(ftdi) usb to serial, it worked perfect. After much traffic logging it appears to be a windows problem although I was able to use John's(Tunercat) with Win7 and the serial port but the logging showed an incredible amount of retries that I don't normally see. It's like the newer windows stuff doesn't understand the original serial stuff, bleh.

  10. #10
    LT1 specialist steveo's Avatar
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    Quote Originally Posted by Janson9027 View Post
    I was checking the voltage the other day for the reflash, and I checked the voltage across the battery+ junction near the PS reservoir and the voltage really jumps around and does not become steady. Next, I will replace the junction. I wont attempt a reflash, I do not want to brick the PCM.
    I will check and clean the grounds and connections between the ALDL and PCM..
    your wiring is probably all 25+ years old and gm used really crappy wire

    you'll have to go through the whole thing

    on my last fbody i rebuilt the whole harness in my living room, load tested every wire and rewrapped it. took ages

  11. #11
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    Quote Originally Posted by steveo View Post
    i use a set of libraries called QT to make my code work with pretty much any operating system (some people even build flashhack and eehack to run natively on macos or linux)

    unfortunately they dropped support for XP years ago

    so yeah windows 7 minimum now
    Hiya steveo,
    I am hoping it didn't look like I was criticising, your stuff is awesome development and I look forward to any of your future endeavors. I have plenty of lappys for diff stuff :)
    -Carl

  12. #12
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    This is the FTDI I used:
    DTECH FTDI USB to TTL Serial 5V Adapter Cable 6 Pin 0.1 inch Pitch Female Socket Header UART IC FT232RL Chip Windows 10 8 7 Linux MAC OS (6ft, Black)
    https://www.amazon.com/dp/B07RBK2P47...roduct_details

    Is it any good?

  13. #13
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    Quote Originally Posted by Janson9027 View Post
    This is the FTDI I used:
    DTECH FTDI USB to TTL Serial 5V Adapter Cable 6 Pin 0.1 inch Pitch Female Socket Header UART IC FT232RL Chip Windows 10 8 7 Linux MAC OS (6ft, Black)
    https://www.amazon.com/dp/B07RBK2P47...roduct_details

    Is it any good?
    Haven't personally tested that one, but according to the reviews it's a real FTDI and is 5V logic, so it should be fine.
    1990 Corvette (Manual)
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