I have used mine some more and done some live data logging while driving. It seems to work as a real GM tech2 from the dealer did back when I worked at the dealer. No complaints. Especially for the price. I cannot adjust the speedo on my truck for bigger tires. That its the TCM and I have an allison transmission. I was able to change it in the ABS module, but that doesn't drive the speedometer. I don't know if this is true for other vehicles.