E38 reflash

[First c10]

Hey guys.
I rebuilt my 6L80 Transmisson and started having trouble with a weird shift when you first start up the truck and put in drive and start going. I talked with Mike at century transmissions and we tried a few things. Nothing seams to work. He did say it has to be in the tune because it only does it when it is first put into drive after starting. Once it shifts in to 2nd for the first time it doesn’t do it again until you shut truck off and start again.

He said that possible the tune is corrupt and the ECM/TCM will need to be re flashed By GM. Mike said that hptuners only alters a small part of the actual tuning GM configured so a stock tune from the repository it’s the same.

Anyone had this done before?

[First c10]

anyone???

[BR3W CITY]

Whats the actual problem? All it says is a "weird shift". Is it not going into 1st or?

[First c10]

Hey brew
Ok so When I first start the truck and put in gear and start to drive off I hear a whine in the trans about 6 times and if I drive it when the whine is happening and the truck shifts it shifts very hard like two or three times. This is not normal shifting. But after the first initial shift it never does it again unless I shut the truck off restart it and drive again. I hope this makes sense

[Madkidd007]

Now I’m no expert but I don’t believe your ecm is the issue, well more like I think it could be something else. If you’re running an E38 then you should also be running a transmission controller also. I know I’m my trailblazer ss the engine and trans have separate controllers and everything I’ve seen if you have the wrong trans controller it can do some weird stuff. I’d research into that

[First c10]

Thanks for the response. The ECM is a E38 and the ECM / TCM and all components are all from the same vehicle. so they should work.
the issue is the initial shift. After that it drives fine

[BR3W CITY]

What was the donor for all this? The E38 can control the 6-series trans using their own tcm (pan mounted) or the seperate T42 TCM to control 4-series trans'.

The OS and trans segment would need to match; so when you say they came from the same donor; do you mean same exact truck, or same model/type/year?

[First c10]

2011 GMC 1500 LTZ truck. E38 with TCM in Pan

As I said earlier My trans guy said since it was only at the beginning and not every time it shifted from 1 to 2 to 3 etc, and only after a start up it had to be programming. not the internals of the trans. he told me to take to GM and have it re flashed. has anyone had to do this since the truck is not a 2011 anymore.
Can I license another file and upload to the PCM from like from another VIN of the same year and model truck??? or a Camaro etc?

[BR3W CITY]

The segment swaps can be done in HPT. I'm not sure why he doesn't think that would work, unless he's under the impression that the issue is in a sector specifically not being written?

I'd see if you can get it reflashed through HPT first. It needs to be done as a complete overwrite, not an update or quick flash. A truly corrupt flash is fairly uncommon.

In terms of trying to get a dealer to do it? Hit or miss. Some cool service advisors may let you bring it in and throw an TechIII on it, but I have not had luck getting favors from any of my local dealers.

[Madkidd007]

Well here is a key question, did you have a chance to drive the donor vehicle at all? Seems strange that all matching items are not happy, I tend to think something sticky in the trans. But the one item I do not personally do is internal trans work, so I’m just thinking here.

[First c10]

This package has been in the truck for 6 years with no problems until the rebuild (due to a cracked 1-2-3-4 piston) and tune. The tune was installed before the truck was driven for the first time after rebuild. I will pull it if I know what to fix. I think it was in the trans but mike at century is telling me it’s in the tune!!!

[Wgesnerjr]

you could try getting another matching ecm and have modified to remove vats and such, install and see if trans act differently. Then you can rule out tune with losing your current set up.

[homemade87]

When I had to replace my trans in my 06 I was told I had to reset the trans learn or there could be problem or damage to the new trans . Apparently when you have a trans doing odd things the tcm tries to learn those things to compensate . When you put a rebuilt or new trans in it will still use the things it has learned to the new trans and can cause problems or damage .


I have a buddy that has a tech 2 but I could not get it the re set the trans learn . I had a diablo tuner on it and I think it was the problem . I trailered it to the dealer where I know the master tech and he could not reset it either . So he had to reload the stock tune and that fixed the problem and reset the trans learn .

After the reset I could tell the trans was learning the new trans . Shifts were a little funny but after a month or so of reg driving it all cleared up .

A long way to tell you to get the trans learn reset and see what it does . This is something that most dont know about but if the old trans has learned some bad habits it will apply them to the new trans .

[Madkidd007]

I can see a relearn 100% on an exchange unit, but if the trans that came out was rebuilt and no electronic parts swapped I would say no relearn. Do you happen to have the previous tune saved and can just reload it and go from there?

[homemade87]

Originally Posted by Madkidd007

I can see a relearn 100% on an exchange unit, but if the trans that came out was rebuilt and no electronic parts swapped I would say no relearn. Do you happen to have the previous tune saved and can just reload it and go from there?

The relearn has nothing to do with electronic parts . It has to do with the tune the pcm has self learned .

[First c10]

Hey guys all good info.
I have tried everything when it comes to the tune and hptuners except installing a complete new tune other than the altered stock tune. I have tried many things in the tuning.

I actually own the Duplicate of truck that the package came out of. The swap was a 2011 1500 with a lc9 and 6l80. Can I license that tune from the stock 2011 1500 and upload to the swap package? Or do I just pay GM to reflash?