The dashlights are dimmed by rotating the headlight switch knob when it is pulled either halfway or all the way out. Rotate clockwise to dim, counterclockwise to brighten UNTIL it hits a clickstop, the if you rotate it further counterclockwise past the detent, you turn on the domelights. If you need to replace the switch, you will need to release the stem with the knob on it. This is accomplished by pulling the knob all the way out. While pressing the little spring-loaded button on the opposite side of the switch from the harness plug, push the knob slightly in to release, and then pull it free. The dimmer coil for the dashlights is external on the end of the switch nearest the dashboard, and it becomes dirty and corroded over time. If you rotate the knob slightly and the dash lights cut out, this could be the problem.