6.0L with E78 ECM VSS

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09-10-2020
DanSchafer93

3 Attachment(s)

6.0L with E78 ECM VSS

Hey y'all,

I can't figure out what it is I am missing here and looking for some help. I have a 6.0L from a 2012 gmc Sierra. Its set up for standalone since its mated to a NV4500 Manual trans. I am trying to set it up to have a VSS. I currently have a Dakota Digital passthrough p/n sen-01-4160 (8Kppm) on the speedometer cable on the back of the transfer case being fed to a dakota digital signal converter p/n SGI-100BT (128K ppm). The idea is to create the 8K ppm signal from the passthrough, amplify it to 128K ppm through the signal converter and I have tried sending it to each of the following pins on x3- 48, 49, and 55. I have attached the pin out for the entire x3 connector for the ECM. regardless of what I am trying I just cannot seem to get anything but the flickering 158 mph on my logs.

I attached a log file, my tune, and the ECM connector pinout.

Any ideas would be helpful!

Thanks,

Dan
09-10-2020
Jon S.

Plenty of threads on the dreaded "158 MPH" scanner reading.

Gen 4 LS ECMs (E38 / E67 / E78) that were originally paired with an automatic transmission, that are subsequently paired with a manual transmission, will have this issue with the SAE VSS PID. The ECM's internal DMA VSS PID, will generally display the correct speed (if programmed correctly).

The short answer is - your Truck E78 ECM will not process a speed input, unless a TCM is connected.

If this is a conversion vehicle, then switching to an E38 or E67 ECM (programmed for a manual transmission) would likely get things working.
09-11-2020
DanSchafer93

I know there are a lot of threads out there with the 158 MPH reading.... Not a lot of those are running a E78 ECM. It is quite different from the E67 or the E38. Also I would rather not switch ECM's because it is my understanding that this is the ECM needed for VVT. Also, the only other application I know of that uses this ECM besides the L96 Engine is a 2012 Chevy Cruze 1.4L and on that you can run standalone just fine with the VSS working. https://forum.hptuners.com/showthrea...light=1.4L+vss. This should be possible and not nearly as hard as it has been to try to get figured out.
09-11-2020
5FDP

The E38 does VVT. The 2500/3500 trucks used the E38 from 2007-2010.
09-11-2020
Jon S.

Quote:

Originally Posted by DanSchafer93

I know there are a lot of threads out there with the 158 MPH reading.... Not a lot of those are running a E78 ECM. It is quite different from the E67 or the E38. Also I would rather not switch ECM's because it is my understanding that this is the ECM needed for VVT. Also, the only other application I know of that uses this ECM besides the L96 Engine is a 2012 Chevy Cruze 1.4L and on that you can run standalone just fine with the VSS working. https://forum.hptuners.com/showthrea...light=1.4L+vss. This should be possible and not nearly as hard as it has been to try to get figured out.

Up to you. From your Forum posts, you have been pissing around with this for at least two years.

Both the E38 and E67 ECMs will control VVT and AFM - and are very conversion friendly.

The Truck E78 ECM is not conversion friendly - that is why no one uses these in a conversion vehicle.

The Cruze E78 ECM that you mentioned is offered with a manual transmission - hence why the direct VSS input will work with that specific platform.

You can continue being frustrated, or you can switch the ECM, and finally be done with this project.
09-21-2020
DanSchafer93

5FDP- Do you have a recommended website/ place to find a E38? I just would have to re-pin at the bare minimum correct? I am not super stoked about the Harness prices..

Also, I would rather work with HP to develop the E78 so not everyone with a E78 has to swap the ECU. I have been putting in tickets in hope of trying to fix these issues but would rather make sure I am not missing anything first. I am not a coder by any means, but I feel like this SHOULD be possible to do regardless of the ECM. It may take an OS patch of some sorts or something but I feel like it can be done if I get the proper support.

Jon- I don't mind that my project is taking time. I enjoy learning the process and building the best build I can. This project will probably NEVER be done. By choice. If you feel like I am wasting your time, I am sorry for that, but this is the reason for the forums. This is not my JOB its a HOBBY. This is also why I am not going to throw roughly $1200 at the conversion kit for the harness, E38 ecu, etc. If I was going to spend money like that, I would go with a Haltech and be done.
09-21-2020
Jon S.

Quote:

Originally Posted by DanSchafer93

... Jon- I don't mind that my project is taking time. I enjoy learning the process and building the best build I can. This project will probably NEVER be done. By choice. If you feel like I am wasting your time, I am sorry for that, but this is the reason for the forums. This is not my JOB its a HOBBY. This is also why I am not going to throw roughly $1200 at the conversion kit for the harness, E38 ecu, etc. If I was going to spend money like that, I would go with a Haltech and be done ...

You are not wasting my time - but you are wasting your own time. No need for the shitty attitude - I was actually trying to help you, but you are having a difficult time seeing the forest for the trees - as the old saying goes. An OEM control system can work extremely well, switching to an aftermarket system is a complete waste of money.

In your specific situation, you only need to switch the ECM - not the entire wiring harness. You could do this for very little money, and a few hours of your time.

An E38 ECM from a 2012 LS truck will not cost you very much at a wrecking yard / auto recycler. The E38, E67, E78, E92 ECMs all use the same terminals (crimp on pins).

Your E78 has Blue, Black, and Grey ECM connectors. An E38 has Black and Grey connectors. The Black connector is the SAME with an E38 and an E78 - you would only need to get an E38 Grey connector.

You then simple move your existing ECM wires from the E78 connectors to the E38 connectors - no cutting, and no crimping. People have been doing this exact same thing for years, when swapping from the Vortec "Black Box" PCMs to a P01 PCM - your situation simply involves more modern computers.
09-21-2020
DanSchafer93

Jon- My intention was not to seem like I had a shitty attitude. Like I said previously I do enjoy learning and even just in your last message I learned about the black connector being the same. I really appreciate that kind of knowledge if I do decide to go that route. I assumed the pins would be the same type and etc. but thank you for solidifying that for me! One question I do have is could you take a E38 from a 5.3L and just reflash it for a 6.0? I suppose it would be the exact same thing wouldn't it?
09-22-2020
Jon S.

Your 2012 L96 6.0L features VVT. A wrecking yard 2012 Silverado / Sierra 5.3L ECM will likely be from an LC9 - which features VVT and AFM, and is Flex Fuel compatible.

Both of the above use the same Throttle Body and Accelerator Pedal (APP) - so component compatibility should not be an issue. Obviously, if you begin with a 5.3L E38 calibration, it will need to be adjusted for your 6.0L engine.

The 2012 Truck E38 ECM would have been released with OS 12647991. There was a GM update to OS 12653249 - this is the OS that will be the most user friendly for your specific conversion - with respect to the speed signal from a manual transmission type input.
09-22-2020
Jon S.

I answered your 5.3L question - but omitted the most elegant option.

If you are able to find an E38 ECM from a 2012 model year 2500 / 3500 series Express / Savana / Suburban - with a 6.0L engine - this would be ideal. There would then be no need to adjust the base calibration for your engine.

The same caveat applies - OS 12653249 is the one that you want.
09-22-2020
DanSchafer93

Where would I find the new OS then? In the Tune Repository? Or is there another way?

Also once I have it, can I just re-flash the entire ECM and it not get super upset?
09-22-2020
Jon S.

1 Attachment(s)

Sorry ... let me break things down a little bit.

Step one - locate a "likely" E38 ECM at a reasonable price. The photo attached below is a search result from Car-Part.com from Ohio locations - a 2012 Express 2500 6.0L E38 ECM for $60.

This is the same engine that you have.

Step two - read the E38 ECM using HP Tuners (do not license it - just read it)

Step three - determine the OS (12653249 is ideal -12647991 could still work)

This is what I was suggesting - a low cost E38 ECM from your local wrecking yard - and do not license it until you are 100% certain that you will use it.

To answer your question - with the Gen 4 ECMs you cannot change the OS using tuning software. That is why it is crucial to choose wisely from a wrecking yard - such that the calibration in the E38 ECM will work for your conversion project.

The above is depicts the low cost, DIY approach. You could purchase a new E38 ECM, and pay someone to VIN program it to exactly what you need - however with some carefully searching of your local wrecking yard, you could get nearly the same thing - for a fraction of the cost.

Attachment 103450
09-22-2020
DanSchafer93

That makes sense...
I could have sworn that I seen someone in the forums previously changing the OS of their ECM but then again I could just be crazy!

Thanks for laying it all out there for me. I really appreciate it.
09-22-2020
blindsquirrel

Yes, you can change it with HPT... and it will be wrong. People do it all the time and then wonder why they have all these weird phantom issues that can't be solved.
09-22-2020
5FDP

Changing OS's on older computers like the P01/P59 may be what you read about, those are different than the GEN 4/5 computers.
05-21-2021
Brooks3racing

Dan did you get this working? I?m looking at swapping my 2011 2500hd e78 over to an e38 for a boosted application and want to keep all the functionality of a stock truck and 6l90 tranny. Would be helpful to know if this works before repinning en ecu/ harness.
09-06-2023
naf

Quote:

Originally Posted by Jon S.

Sorry ... let me break things down a little bit.

Step one - locate a "likely" E38 ECM at a reasonable price. The photo attached below is a search result from Car-Part.com from Ohio locations - a 2012 Express 2500 6.0L E38 ECM for $60.

This is the same engine that you have.

Step two - read the E38 ECM using HP Tuners (do not license it - just read it)

Step three - determine the OS (12653249 is ideal -12647991 could still work)

This is what I was suggesting - a low cost E38 ECM from your local wrecking yard - and do not license it until you are 100% certain that you will use it.

To answer your question - with the Gen 4 ECMs you cannot change the OS using tuning software. That is why it is crucial to choose wisely from a wrecking yard - such that the calibration in the E38 ECM will work for your conversion project.

The above is depicts the low cost, DIY approach. You could purchase a new E38 ECM, and pay someone to VIN program it to exactly what you need - however with some carefully searching of your local wrecking yard, you could get nearly the same thing - for a fraction of the cost.

Attachment 103450

Hey Jon

I have a 2009 Escalade engine and ecm, coupled to a t56 mag trans. I have a small problem where the gateway I use to operate the dash only speaks Truck GMLAN. I tried flashing the vette OS, and the speedo in the scanner functioned properly, but the dash did not work at all. Go back to the truck OS, and the dash functions, but the ECM is lookin for a TCM signal that is not there so the speedo on the scanner reads 255kph all the time.

Will flashin a 12647991 or 12653249 OS onto my ecm help me keep the truck GMLAN and solve my scanner 255kph speedo issue?

We do not have many vans in our junkyards, and if I look for an ECM online, most ppl will not ship to me