1995 LT1 Flashing Issues EEHack

[boxsport]

Hello guys,

I hope someone can help me out.
I'm trying to flash a 95 ECM on the bench using EEHack, but i´m getting an error when doing the flash and i'm not sure what i'm doing wrong...
If someone can see the pictures and help me with this i would be very thankfull....
ECM: 16188051

Thanks

[steveo]

i did just answer this in a PM but just in case anyone else is reading:

VPP voltage if you aren't aware is a signalling voltage to the EEPROM in a state where it can be erased/reprogrammed. without VPP it's 'safe' to twiddle any pins without actually damaging information on the EEPROM, we need to supply voltage to that pin to do any damage to it.

unfortunately that flash routine built into eehack does not tell you why the VPP apply routine failed, it just gives up. my new flash tool will tell you but it's not quite ready yet.

if you are really curious why its failing, open eehack's debug log and check the 'verbose' box it will dump all of its bus messages. right after it fails it'll probably spit out a short message containing a return code, which i could use to tell you why its failing.

the VPP apply routine first checks the IGN voltage (it has to be 10.8 to 16 volts so that's unlikely to fail) but then it tries to apply VPP voltage and tests its output, which will fail if input voltage is insufficient. it must be in a very narrow range, so if your input voltage is too low, it'll fail. usually 11.5-13.5v of clean input is fine, though.

what is the ignition voltage in eehack if you just run a datalog for a few seconds?

be very careful flashing until you find out whats going on, a small failure might brick that ecm.....

[boxsport]

i did just answer this in a PM but just in case anyone else is reading:

VPP voltage if you aren't aware is a signalling voltage to the EEPROM in a state where it can be erased/reprogrammed. without VPP it's 'safe' to twiddle any pins without actually damaging information on the EEPROM, we need to supply voltage to that pin to do any damage to it.

unfortunately that flash routine built into eehack does not tell you why the VPP apply routine failed, it just gives up. my new flash tool will tell you but it's not quite ready yet.

if you are really curious why its failing, open eehack's debug log and check the 'verbose' box it will dump all of its bus messages. right after it fails it'll probably spit out a short message containing a return code, which i could use to tell you why its failing.

the VPP apply routine first checks the IGN voltage (it has to be 10.8 to 16 volts so that's unlikely to fail) but then it tries to apply VPP voltage and tests its output, which will fail if input voltage is insufficient. it must be in a very narrow range, so if your input voltage is too low, it'll fail. usually 11.5-13.5v of clean input is fine, though.

what is the ignition voltage in eehack if you just run a datalog for a few seconds?

be very careful flashing until you find out whats going on, a small failure might brick that ecm.....

Thanks for the quick answer...
I saw your PM now.
I will do some tests on the afternoon / night and see if i can get that Log messages and let you know...
Questions: from the USB-TTL adapter, do we need to connect the VCC to anything?
I just have the GND, RX and TX connected...

[kur4o]

What is the purpose of that blue box between the pcm and power supply?

[boxsport]

What is the purpose of that blue box between the pcm and power supply?

if your asking about the blue PCB were the cable go conneted, its and OBD2 adapter / PCB so that i can connect ECM/ECU, Dash, Immo box, etc for some bench tests...
In this case, i´m just using it to supply voltage and ground to the ECM, because it has several pinouts / connections that makes bench tests easier for me...

[steveo]

Thanks for the quick answer...
I saw your PM now.
I will do some tests on the afternoon / night and see if i can get that Log messages and let you know...
Questions: from the USB-TTL adapter, do we need to connect the VCC to anything?
I just have the GND, RX and TX connected...

nope, just rx/tx and ground.

[boxsport]

nope, just rx/tx and ground.

Ok, so i just tried again and still same error...
I'm uploading here the log you mention to do and also the picture of the "Stability Test" so that you can see that i got no errors...
Doing the flash, im using both "Skip Unused Regions" and "Insert Patches" options activated (not sure if this is the way).
As i remember i also read with those options activated...

Can you take a look at the log and see if there is anything i can do to solve this?
Also, about the voltage, when i tried this minutes ago it was giving me 13.6V.
I also made the test using 12V showing on EEHack and still same problem...:confused::confused::confused:
By the way, i tried to change VIN and it worked. I made the VIN change without any problems...
Can this be related to the COM por configurations? i have it setup with "1" in latency and speed with 9600 (Default)

Thanks

[steveo]

yeah the vpp voltage isn't sufficient, maybe its the power supply or a connection. check all your connections and power the ecm from a charged battery rather than your power supply to see if that works.

[boxsport]

yeah the vpp voltage isn't sufficient, maybe its the power supply or a connection. check all your connections and power the ecm from a charged battery rather than your power supply to see if that works.

i just went up to 16v and still same error...
need to get a battery or a battery charger to test this.
I just realize that the USB-TTL adapter that i have has a Fake FTDI chip on it...(:mad1::mad1::mad1:) Can this be also the reason for this not to work?

Thanks

[steveo]

i don't think its a communication issue as it appears the command to set VPP is uploading and executing just fine, but after applying it, it's out of range. i would assume a noisy power supply or some kind of resistance. what is the battery voltage reported in the eehack datalog?

[boxsport]

i don't think its a communication issue as it appears the command to set VPP is uploading and executing just fine, but after applying it, it's out of range. i would assume a noisy power supply or some kind of resistance. what is the battery voltage reported in the eehack datalog?

i might need to review all the wirings and probably make new cables because i´m using a protoboard and some "dupont" cables that like you say might create some noise...
the voltage i reported is the value that shows on the eehack "ECM voltage".
i will also try with another laptop i have just to make sure that its nothing to do with the laptop...

i will keep you posted

[In-Tech]

An electrolytic cap on the power of your breadboard should clean it up.
40v or higher, ~10-100uf should do it ;)

[boxsport]

An electrolytic cap on the power of your breadboard should clean it up.
40v or higher, ~10-100uf should do it ;)

thanks. i will try that. i should have some of those in some place here...

[steveo]

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.

[steveo]

don't suppose you have an oscilloscope, do you?

[boxsport]

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.

[boxsport]

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...

[kur4o]

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.

[In-Tech]

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.

[steveo]

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

i swear i fixed that bug

[boxsport]

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...

[boxsport]

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...

[kur4o]

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.

[steveo]

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.

[boxsport]

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?

[kur4o]

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.

[NomakeWan]

Not possible, no. The circuitry is different.

[steveo]

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

[boxsport]

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...

[boxsport]

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?

[steveo]

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.

[boxsport]

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

[steveo]

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.

[steveo]

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. 15349

[boxsport]

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. 15349

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

[steveo]

vpp voltage is only set high when the program tells it to

[boxsport]

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_VX3y0VKATiTGP7W4OVt8xVskZ0XPfq2Be62Q_n bo
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

[boxsport]

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...

[NomakeWan]

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.

[steveo]

the error comes up once in a while. i'm sure it'll be okay

[boxsport]

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

[boxsport]

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...