WARNING: This page is about a different car, the 2002 GMC Safari, 2002 Chevrolet Astro, 2001 GMC Safari, and 2001 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
The number below refers to the step number on the diagnostic table:
3. Tests for a magnetic field near the ignition lock cylinder.