I have a 2000 GMS Sonoma, 4.3L, A/T, 4WD, the 10A Crank fuse blows quite often.When it blows the load side of the fuse is directly shorted to ground.A mechanic stated it was the Park/Neutral Switch and replaced it some time ago. The problem persisted. We thought it was a intermittant short to ground in the wiring. I ran new wires to the P/N switch and the 4WD Control module, this did not help the problem. By accident I hit the load side of the fuse with +12V, the starter indexed and the short went away. I have since replaced the starter and the problem still comes back. Everytime it occurs, if you zap the load side of the fuse with +12v, the starter will index and the short goes away. You can then replace the fuse and the truck will start. I have also replaced the ignition switch thinking there might be a short somewhere in that circuit.