Today was my first encounter ever with this error message, after searching I realized this was a pretty common issue with LB7s. Truck is a 02 LB7 that my buddy just purchased so the past history on it is unknown. I went to full flash a DSP file into the truck today and kept getting the $0537 error. I tried everything from using v8 and 7.5, removing fuses, checking the extra flash options and anything other I could find searching the forums pertaining to that error. Here are 2 pics from what I could gather from the truck. Any help greatly appreciated!