Join Date: Dec 1999
Location: Meridian, Idaho
It's been awhile since I worked on a 68 RS but there should be 1 vacuum line running into to your firewall and to the switch. So to answer your question is yes it does have vacuum going to your switch. The valve that you are flipping is for manual open. I used it to leave open to clean the headlights. Chevy put it in just in case of a problem that you are having now. When you pull the head lamp switch, you should here a slight hiss at first. If not, there is a possibilty of blockage, not hooked up, or it's a bad switch.