checksum question

[upyas]

When i am loadidng a tune into a ecu and i get the checksum question and the option to change the checksum, when i get this prompt the ecu gets bricked.

is there a way to stop the ecu from being bricked? do you have to change the checksum to the one it suggests ? i have bricked a few ecus because of this prompt

WHat is the correct way so stop the ecu from going offline forever?

[antus]

for the foobar pcm with eagle operating system and the floofal pc software the answer is yes, probably.

no, jokes aside, you need to tell us details, like what pcm, what software, what message, what have you edited... and so on. the question cant be answered with none of those the details because the answers are different depending on context.

but guessing from only that you posted in holden aldl pcms area, if you mean the VX/VY flash PCM you need to correct the checksum when you are doing a bin write (not required for clone) because the operating system checksum includes the eeprom which is in the pcm not the file sent, so there is no way to pre-calculate it on the PC, the flash tool has to do it at runtime.

[upyas]

i have a bin file saved that i want to write to VY VX ecu that has worked in another ecu

i want to clone the ecu that i took the tune out of if that makes any sense? when the ose flash is finished there is a square box prompt with a checksum value in it, it has a value in blue in the box and it mentions another checksum in the box and it is asking you to type the checksum, how do you get past this without bricking the ecu ?

where do i get the checksum? i cant connect a scan tool because this is part of the write in the ose flash tool

the flash tool is not setting the checksum like it does when you do a calibration upload and it is asking me what checksum it should use

[antus]

when you write bin it asks you at the end of the process if you want to correct the checksum. it gets what it needs from the pcm to do that on the first way through (I think its like 4 passes, 1 per bank) then it does it all again and fixes the sum. After that you can and should do calibration only writes. I am not sure about this sum box you are talking about, and I don't use that PCM so dont have a lot of experience, I just know thats the process.

[pman92]

Yes you have to allow it to correct the checksum. There also an option in preferences to do it automatically.

It would be good if it didnt write everything, then determine incorrect sum, erase everything and write it again. Instead if it could pre-calculate by reading PCM before write, or only erasing the section it needed to re-write the checksum.

But I'm not sure if the way it is done is a limitation of the PCM. Either way VL400 isn't around any more so I don't think it will ever be changed. It's not a big issue, just takes twice as long to write.

[upyas]

im going to brick another ecu so i can get some screen shots

[pman92]

im going to brick another ecu so i can get some screen shots

You dont need to. We know what you're talking about.

1. The file you're writing needs to be complete (not just calibration).
2. When it askes if you want to write the eeprom area, you need to either make sure that area is present in the file (they didn't "clear registers" when they read the file) or do not write that area.
3. When it calculates and displays the correct checksum at end, and askes if you want to write it, you need to select yes.

Dont brick another ECU.
Post up the file you're trying to write and someone might verify it is a complete and valid file for you

[Rhysk94]

Video showing how to do it.
May be easier to follow along than just reading words.

https://youtu.be/DDZe__r25DQ?si=r3j02AZKZDErLYeF

[Gareth]

They can be unbricked by using SPS to update

[upyas]

what is sps and where do we get it from?