Without a scan tool
WARNING: This page is about a different car, the 2001 Pontiac Bonneville and 2000 Pontiac Bonneville. However, it is still accessible from the selected car via links, so may be relevant.
Turn off ignition. Remove IP fuse (10-amp) from rear fuse block (located behind rear seat, on driver's side). Fuse must be removed for more than 60 seconds to clear system memory. Reinstall fuse.