When the ignition switch is in the RUN position, voltage is available through the TURN B/U fuse to the backup lamp switch. With the transaxle in reverse, voltage is available to the left and right backup lamps, which are permanently grounded. When voltage is available to CKT 24 (LT GRN), the backup lamps illuminate. CKT 24 (LT GRN) also supplies input to the electrochromatic rearview mirror dimming function. Connection is also available for the trailer-tow capability.