Has anyone had thier DIC change it's own calculations? For example, when I would fill up the tank(between 28-30 gal.) the range would read 600 miles or more. The DIC was also showing mpg's in the 20 range. I just filled up yesterday with 28 gal. and it shows my range as being 390 miles and 17.9 mpg. My main concern is that my DIC was pretty darn accurate and then all the sudden everything is inaccurate. Even the mpg's are lower when hand calc'd which makes the range issue even worse. By the way I do have a long bed with the 34 gal. tank and no additional tank. I haven't done anything to the truck recently but we did just get back from a 700 mile round trip to Pismo with beach camping and pulling the loaded toyhauler.
I have read about all of the DIC inaccuracies on here but mine didn't start out that way. Also, I have been running my Predator for over a year now, so I can't see that causing it and I have calibrated for my tires. Anyways, I was just wondering if it's worth mentioning to the stealer cause I have to take it in for steering wheel lights out. Hope I haven' left anything out, if I did just ask me. Thanks.

I would guess it is the Predator. My DIC use to read 34 MPG now it reads 21.7 MPG.

Your 700 mile trip driving loaded most likely is what changed things. Try reseting the MPG on the DIC and letting it relearn.

It would be nice if GM would add an calibration function to the DIC like Scangage.

Thanks Drew, I was thinking about putting the stock tune back in it and resetting things and letting it re-learn. When I filled up on Tuesday I did reset the MPG,fuel used and trip miles but I will do it again to see if that helps. I think you are right about the Predator though....thanks again.

hand calc is the only "accurate" way...Predator is the problem and resetting it will not fix the problem...most tuners do this...

06Dmaxpwr....I know you're correct about hand calculating being the only way to go. As I was thinking more about this I wonder if it was calculating the range based on my previous mpg. When i filled up it was only 11.5 and that would give me an approximate range(DIC calc.) of 391. I bet that is it. I am going to reset the mpg before I fill up next time.
Thanks you guys for the replies.

Before I installed my predator my DIC was always withing .3 mpg of my hand calculated mileage, however now it generally reads 4-5 mpg higher than the hand calculated mpgs.

FWIW I changed both the tune and tire size when I got the predator, all the resets in the world haven't "fixed" the mpg reading.