Welcome to FF!
Thinking the car might be new to you since you just joined up here.
Does the switch have a fog light symbol on it? It's an extra symbol besides the Off, Running light, headlight symbols. Looks like the headlight symbol but with a slash thru the angled "light beam" hash marks.
Could be a prev. owner either didn't complete an install, or substituted a std. switch when the fog switch gave up if you don't see that.
"Rubber Side Down"
Focus Takeover #003 / Tarbo Fan #003