Without knowing which bike you are talking about, the display may have the option, but the controller MAY not have the physical connection. Check your controller, you might have a 2 pin JST connector or a 2 pin WaterPlug that isn’t plugged into anything. Colors are irrelevant, could be black-yellow, black-red, black-white, anything really, but those seem to be most common. If you see a connection like this, test for voltage BEFORE toggling the light on, via the display. Test for voltage after you turn the headlight feature on. Is there a change? You would see full pack voltage, so USE CAUTION. If you find, and verify, a headlight connection, then you just need to find a light that will except the voltage you “see”. Positive-positive, negative-negative. Then, you all set.