Battery positive voltage (B+) is supplied at all times to the REVERSE relay coil through the rear fuse block. Battery positive voltage (B+) is supplied at all times from the rear fuse block NSBU Fuse to the REVERSE relay switch. The powertrain control module (PCM) sends a class 2 message to the rear integration module (RIM) indicating that the gear selector lever is in the REVERSE position. The dash integration module (DIM) sends a class 2 message through power moding that the ignition switch is in the ON position. When these conditions occur, the RIM grounds the REVERSE relay coil via CKT 646 (DK GRN). The coil is energized, closing the switch contacts. This supplies battery positive voltage (B+) to the backup lamps via CKT 24 (LT GRN). The backup lamps are both permanently grounded through CKT 850 (BLK) to G402, so both backup lamps have power and ground, and then light.