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Thread: 1995 LT1 Flashing Issues EEHack

  1. #31
    LT1 specialist steveo's Avatar
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    it's really uncommon to have issues with these ecms

    the vpp voltage has to be in a very narrow range

    you never answered me what the ecm voltage is according to the eehack datalog.. connect, go to the tab that says *Main, and look for [IGNVOLTS]

    if you're willing to open the case you could probe pin 1 on the eeprom chip an see what the vpp voltage actually is once it's set high. it needs to be 11.4-12.6 volts.

  2. #32
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    Quote Originally Posted by steveo View Post
    it's really uncommon to have issues with these ecms

    the vpp voltage has to be in a very narrow range

    you never answered me what the ecm voltage is according to the eehack datalog.. connect, go to the tab that says *Main, and look for [IGNVOLTS]

    if you're willing to open the case you could probe pin 1 on the eeprom chip an see what the vpp voltage actually is once it's set high. it needs to be 11.4-12.6 volts.
    about the voltage, i mention some posts back that value you asked. after that i've been checking the voltage in that "tab" all the time...
    now, i've open the ECM and got surprised... Its a mess inside...
    i'm sharing some pictures for you guys to see.
    Now, on the picutures i'm posting i marked what seems to be some ceramic capacitors damage.
    Does anyone know what would be the values for those?
    After i made some cleaning, the only thing that seems to be with some burned marks/color is the silicon protection on top of those components. i cleaned that up and the components seem to be ok. but something happend there...

    About checking the voltage in Pin1 from the Epprom, i will try to do that, but do you have any pictures or can you point to any of the pictures i'm posting where should i check that out?
    Thanks

  3. #33
    LT1 specialist steveo's Avatar
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    the goop they coat the board with will protect from quite a bit of moisture, and it always makes stuff look worse than it is, but i would consider that ECM a throwaway myself given the evidence of water intrusion one that one side..who knows what you aren't seeing.

  4. #34

  5. #35
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    Quote Originally Posted by steveo View Post
    since you asked, here's the eeprom and how to find the vpp pin. the pin should lead to a trace and to a nearby test point. vpp.jpg
    thanks.
    I know this ECM probably belongs to the "Spare Parts" division now, but i'm trying to see if i can find anything...
    i already found a "broken" track and fixed it, but still no luck...
    just checked the VPP voltage and it get 1.8 (+-), so i will try to look close those circuits to see if i can find anything.
    Again, thanks for all the support

  6. #36

  7. #37
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    Quote Originally Posted by steveo View Post
    vpp voltage is only set high when the program tells it to
    I was able to get (buy) another ECM with the same service number, so i Hope that it arrives on Tuesday to do some more testing...
    tomorrow i have an electronic frien to come over to look at the PCB and see if we can find any issue on the components to see if i can make this ECM to work...

    About the Blue PCB you guys asked, i took some high quality pictures (i think they are OK) for you guys to see.
    You can download the pictures on this link:
    https://mega.nz/file/Z1d0FAwJ#Tg_VX3...XPfq2Be62Q_nbo
    Its too big to post here.
    So, if you need any info on this "card" let me know and i will share all the info you need.

    Cheers

  8. #38
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    Quote Originally Posted by steveo View Post
    vpp voltage is only set high when the program tells it to
    Hello guys...
    Good News...
    I got yesterday the ECM and just tested minutes ago the flashing, and it went Well...
    Just need to clear some doubts:
    When it finished the flash process, i got "Cant Communicate with T-Side". For the comments bellow this error, this doesnt seem to be a bad thing.
    Just would like to clear this up...

    I made a read after the flash, and it gave the message about the ECM being already flash by EEHack. Can you check the picture and tell me if this is OK?

    What i did was, i received the ECM, read and save the Original Bin from the Replacment ECM, and just loaded up the Bin i had modified to remove "Vats" from the Bad ECM (the one i was trying to flash for days). I then updated the VIN number.

    Can you guys confirm me if tthis will be OK? (i know i still need to test in the car and see if nothing pops out...)

    I also have a question about the "Little Lid" that these ECMs have.
    I've been reading and it seems to be for the Knock Sensor.
    Some models have 1 some models have 2. Is this Correct?
    Now, can i just swap that little "box" fro one ECM to the Other?
    Old ECM "box" had number 16251879.
    This "New" ECM has the number 16177700 on it...
    Are they the Same?

    Thanks guys for the Support...
    Stay Safe...
    Attached Images Attached Images

  9. #39
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    Under the lid is the knock module, which is a frequency filter and signal unit for the PCM. Basically the knock sensors send their signal to the knock module, which filters the signal based on a predetermined range programmed into the module, then signals the PCM if it detects knock.

    The pre-96 PCMs used a single knock sensor wire and used knock sensors with a built-in resistor to determine if the sensor(s) were in place. The resistor will commonly go bad without the actual sensor going bad, which can cause a knock sensor fault code. The '96-'97 PCMs used two knock sensor wires and knock sensors from the C3 Corvette without the resistor; they determine whether or not the sensors are working based on whether or not a sane signal is actually being received.

    Keep the knock module that was associated with the vehicle you actually own. If the old PCM was the correct one for your chassis and engine combination, put that module into the new PCM.

    As for your error, steveo will have to chime in probably; it may have to do with you flashing on a bench instead of in an actual car. It looks correct to me however, I'd say you're probably fine.
    1990 Corvette (Manual)
    1994 Corvette (Automatic)
    1995 Corvette (Manual)

  10. #40

  11. #41
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    Quote Originally Posted by NomakeWan View Post
    Under the lid is the knock module, which is a frequency filter and signal unit for the PCM. Basically the knock sensors send their signal to the knock module, which filters the signal based on a predetermined range programmed into the module, then signals the PCM if it detects knock.

    The pre-96 PCMs used a single knock sensor wire and used knock sensors with a built-in resistor to determine if the sensor(s) were in place. The resistor will commonly go bad without the actual sensor going bad, which can cause a knock sensor fault code. The '96-'97 PCMs used two knock sensor wires and knock sensors from the C3 Corvette without the resistor; they determine whether or not the sensors are working based on whether or not a sane signal is actually being received.

    Keep the knock module that was associated with the vehicle you actually own. If the old PCM was the correct one for your chassis and engine combination, put that module into the new PCM.

    As for your error, steveo will have to chime in probably; it may have to do with you flashing on a bench instead of in an actual car. It looks correct to me however, I'd say you're probably fine.
    Thanks for the explanation...
    It clear my doubts.
    Cheers

  12. #42
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    Quote Originally Posted by steveo View Post
    the error comes up once in a while. i'm sure it'll be okay
    Thanks. I hope tomorrow or Saturday i can go and test this ECM on the car....
    Fingers crossed....
    Thanks guys...

    I will keep posting any news...

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