My 2007 2500 6.0/4l80 (e38/t42) suburban wont show full when I fill it up. However I can use the scanner and see how many gallons are in it and it will match the fuel capacity amount in the calibration. I filled up and it read 38.5 gallons and the tune shows 38.7 gallons as max, but the scanner also says 87.7% full and thats what my gauge looks like where its at. If the ecm can see 38.5 gallons where is the 87.7% full coming from?