Three buttons are highly unlikely to be standard Ford equipment. It's possible that:
* Aftermarket additions: Previous owners might have added aftermarket lighting or other electronic devices connected to buttons mounted on the sun visor.
* Unusual factory option (very improbable): While incredibly rare, there might have been a very unusual factory option in some specific regions or trims that included additional controls on the sun visors. This is highly unlikely.
* Custom installation: The visors themselves might have been replaced with custom ones incorporating additional buttons.
To know for sure what the buttons control, you'd need to:
* Inspect the buttons closely: Look for any markings or symbols on the buttons themselves.
* Trace the wiring: If you're comfortable with basic car electronics, you could carefully trace the wiring from the buttons to see where they lead. (Be cautious and disconnect the battery negative terminal first!)
* Consult a Ford Expedition forum: Someone else might have experienced this unique configuration and can offer insight.
In short, it's almost certainly not a standard feature of a 2003 Ford Expedition. Further investigation is needed to determine their function.
