The rear fog lamp will only operate with the headlamp switch in the HEAD position. Voltage from the headlamp switch is applied to the rear fog lamp switch and to the rear fog lamp relay coil through CKT 10 (YEL). When the rear fog lamp switch energizes the rear fog lamp relay, the relay contacts close and supply voltage from the DRL fuse through CKT 340 (ORN) to CKT 122 (RED) and to the rear fog lamp.