With the ignition switch in the RUN or START position, battery positive voltage (B+) is applied through the instrument panel (IP) fuse block TMNSS fuse to the park/neutral position (PNP) switch via CKT 139 (PNK). When the gear selector is placed in the REVERSE position, battery positive voltage (B+) is applied to the backup lamps via CKT 24 (LT GRN). Since the backup lamps are permanently grounded at G401 via CKT 1250 (BLK), the backup lamps remain lit until the gear selector is moved out of the REVERSE position.