Head lights will not turn on at low beam

First check the bulbs to see if they're both burned out. If they're okay, the problem has to be the dimmer switch or the wire going to the low beams. At the multi-function, (dimmer) switch, there will be voltage on the light green / black wire when the head light switch is on. We know that's there because the high beams work. Check for voltage on the violet / white wire. If it's missing in the low beam position, replace the switch.