Backup Lamps
WARNING: This page is about a different car, the 2002 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
The NSBU fuse in the underhood junction block supplies ignition positive voltage to the park/neutral position switch. When the driver places the gear selector lever in the REVERSE position, the current flow is from the park/neutral position switch to the backup lamps. The backup lamps are grounded at G401 and G402.