I have a 2003 Silverado 5.3L. it has roughly 1997?? Miles and until yesterday it ran like a sewing machine. It runs rough if it runs at all. CE light is on bought a scan tool and hooked it up. At first it didn't power up but I checked fuses and found the cig lighter out. Replaced fuse scan tool powers on. Says waiting for vehicle to respond and then nothing. Have traced wires and no damage can be found. Any help would be greatly appreciated. It's my work truck.

 

What brand, and does it give you a link error? Also, is the scan tool new?