When I changed from my 2013 explorer XC to my 2017 Explorer XCa, my aftermarket lights would not work in the factory wiring hooked up to the factory switch. Not sure exactly what changed but have a feeling it's something to do with a change in the resistance of the new lights and the ECU believes that they are not working, thus killing the power. Just a guess. If that's true then possibly a set of resistors typically used for LED turn lights may work, I did not try.
I decided that I would power my lights separately, hooked to a Rowe PWM60. So I just needed to figure out how to get the factory switch to work with this. I ended up using a small electronic component called a mosfet(
). The mosfet has three parts, the source, the drain, and the gate. This is connected on the ground side of the wires that power the lights. The ground wire from the main ground goes in the source. The ground wire then leaves the mosfet through the drain and goes to the lights. The third part is the gate. For the gate, I plugged in a single wire on the positive side of the factory fog plugs that are under the front headlight. This positive wire then connects to the gate.
What happens when I turn on the factory LED switch, is that the power through the gate to the mosfet, completes the circuit between the source and drain, thus turning on the lights. When the switch is turned off, the lights go off.
It's a bit complicated but avoided me having to add another switch to the handle bar.