The voltage applies through the TURN-B/U fuse to the following switches when the ignition switch is in the RUN position:

The voltage applies to the left side backup lamps and the right side backup lamps when the transmission is in the REVERSE position. The left side and the right side backup lamps ground permanently through grounds

 G400 and G401 respectively. The backup lamps are on when the voltage is applied to CKT 24 (LT GRN).