Do I need to run new wiring, or does this plug into the existing mirror harness?

This mirror uses your factory mirror wiring—the connectors and circuits are designed to work with OEM electrical points. You'll want to confirm your vehicle has the factory wiring already in place before install.

Will this side mirror work if my Expedition didn't come with power or heat from the factory?

The mirror itself is fully powered and heated, but your vehicle needs the corresponding electrical circuits to activate those functions. If your truck didn't come wired for power mirrors or heating, you'll need aftermarket wiring or a professional to run those lines.

What's your return window if the mirror doesn't fit right or the electrical doesn't work?

Contact ModSupply directly with photos and details—returns depend on condition and timing. Reach out within a few days of receiving it if there's a fitment or function issue.