I've finally found the cause of my problem. It was the Chevystar, which I always thought was desactivated until my van was blocked by it. I've removed the Chevystar and everything came back to normal.
2006 Silverado 1500 4.3 v6 no crank, no start, no spark, no trigger signal between icm and ig coil, no pulse on signal wire from ckp to icm, odb2 coming on but wont connect