Well, after wasting all this time and money, I tried a Banks programmer to see if it encountered the same issue of not being able to write to the TCM. No problem at all! It works great.

This Diablo unit is obviously defective.

Unit returned. Keeping the Banks.

So if the TCM was up to date, is there a ything the dealer could have done? Are you saying they couldn't overwrite with the same data as a reflash?

I was told it was reflashed with the most current software rev.

I'm asking mostly because I'm wondering if I need to confront them about charging me ...

Okay, new computer and the file is attached. Please take a look and let me know what you find.

Thanks!

I have a new laptop on order. Should be able to provide the file in a few days

The reason I asked if I should go back to stock is I was told if I ran an update, you could see the file.

I have a new laptop on order. Should have it in 2 days....might just wait for that.

My computer is down, but I can always revert back to stock so you can see the file. Please confirm and I'll do that again.

I think you missed the rest of my post above. They reflashed it as well. They found no issue whatsoever with the TCM, whether it be reading or writing to it.

Well, I discussed the issue with a GMC dealer today. They hooked up to my OBD and read the TCM without any problem. To be sure everything was right, I paid $159 for them to reflash it.

Unfortunately there's no change with the i3. It still cannot read the TCM. It acts exactly as it did before the ...

Thanks Mike. I appreciate you and your team's help! I'll update once I make that dealer visit.

Is that a known problem? What I mean is, is yhat something that you've seen happen? I've never heard of a tuner having the ability to lock a TCM, preventing it from being readable. Doesn't seem possible.

I plan to have it reflashed by a dealer to the latest factory software rev. That should remove ...

Thanks, but my i3 isn't reading from the TCM, so I don't get any trans options. Learned this today after plenty of time on the phone with a few of you (thanks).

Now the problem is WHY isn't it reading the TCM? Nobody can figure this out.

I just received the i3 and immediately updated it and went out to my Hummer to make some adjustments. I scroll thru the menu looking for the trans shifting tweaks, but there aren't any! WTH?! That's a big reason why I bought this thing and it was specifically advertised for this vehicle as having ...

I think at this point you need to look at your fuel quality. Get some 100 octane unleaded at the track and see if that helps. Try a different gas station as well.

93 octane should be plenty for a 91 octane tune. I've tried gas from 4 different gas stations, even though it's all pretty much the ...

I'm running 93 octane and the 91 octane CAI tune. I've got a 195* thermostat and have the fans set to keep it running at that temp.

I logged a bit and noticed it was pulling out as much as 8 degrees of spark advance!! :shock:

I tried richening it up across the board at WOT and it helped, but only ...

I removed the Jet chip and am now running the CAI 91 Octane tune. I logged a bit and noticed it was pulling out as much as 8 degrees of spark advance!! :shock: I didn't expect this since I always run 93 octane.

I tried richening it up across the board at WOT and it helped, but only a little. I went ...