The auxiliary/fog lamps provide extra light to the road and surrounding environment in dark or rainy conditions. The lamps also give the motorcycle more visibility to other motorists.
See Controls and Indicators → Accessory Switch: FLHTCUTG → Dash Panel Switches. On models equipped with the auxiliary/fog lamps, the switch is on the left side of the fairing cap.
Domestic/Canada configurations: The auxiliary/fog lamps are configured to turn off when the high beam headlamp is turned on, except as required by state/province.
Auxiliary/fog lamps can be configured to remain on or turn off with high beam operation based on legal requirements for each location. See your Harley-Davidson dealer.