With the ignition switch in RUN or START, battery positive voltage (B+) is applied through the IP fuse block T/SIG/BU LP/BTSI fuse 1B via CKT 539 (PNK) to the park/neutral position (PNP) switch. When the gear selector lever is placed in REVERSE, battery positive voltage (B+) is applied to the LH and RH backup lamps via CKT 24 (LT GRN). Since the backup lamps are permanently grounded at G402, the backup lamps remain lit until the gear selector lever is moved out of the REVERSE position.