LMM Programming History & CVN's Explained

[bdr2008]

Is there any new news on the full reset of the ECM history??

[LBZ]

didint work on mine i put a completley new un modded ecm in my truck and it still showed all my old check sums from my previous ecm. wich meens to me the info is stored also somewhere else. ambey the tcm not sure

Has anyone else tried this to see if this is true with all of the LMM's or if this was an isolated case?

It might save a bunch of people money if this idea doesn't work.

[Trippin]

I did a back to back test today where I flashed a core LMM ECM with TIS and recorded the programming history. When the core ECM was installed in a truck, the programming history remained unchanged, meaning the core's programming history was there and did not match the history in the trucks original ECM, which had been previously violated with EFILive.

Flashing the core ECM with EFILive and a non-stock cal yielded a non-GM CVN #.

Flashing the ECM back to a stock cal using EFILive, yielded a factory CVN #.

However, flashing the ECM multiple times with a stock cal, doesn't increment the history count or listing.

[JoshH]

When the core ECM was installed in a truck, the programming history remained unchanged, meaning the core's programming history was there and did not match the history in the trucks original ECM, which had been previously violated with EFILive.

So does that mean that the history is contained in the ECM alone? I'm having a little trouble following exactly what you're saying.

If someone were to flash an LMM ECM with a bench harness and swap it with the stock ECM in a truck that had never been tuned, when they put the original, stock, never tuned ECM back in would the history show the CVN from the modded ECM?

[Trippin]

So does that mean that the history is contained in the ECM alone?

Yes, in the ECM alone.

If someone were to flash an LMM ECM with a bench harness and swap it with the stock ECM in a truck that had never been tuned, when they put the original, stock, never tuned ECM back in would the history show the CVN from the modded ECM?

The history follows the ECM. If the ECM was modded the history will reflect the mod.

Swapping in a virgin ECM will show a virgin history.

[LBZ]

Yes, in the ECM alone.



The history follows the ECM. If the ECM was modded the history will reflect the mod.

Swapping in a virgin ECM will show a virgin history.

So this method should also work with an LBZ then correct?

[winter200]

Thanks Guy.

[Cougar281]

So this method should also work with an LBZ then correct?

As someone else put it, "The LMM is the only one so far that has this little gem".

[Trippin]

So this method should also work with an LBZ then correct?

According to the documentation only the LMM OS contains the history. I'll check some LBZ Ecms with the latest Tech 2 software tomorrow.

[GMPX]

I agree with Guy, the history stays with the ECM, I am 99% sure it is not stored in any other module in the truck.

LMM is the only vehicle to keep track, the option is not even TechII to read history from an LBZ.

Cheers,
Ross