Will this plug directly into my existing wiring?

Yes — this is the OEM assembly, so it connects to your factory harness without adapters. Power and ground wires mate to the door connector you already have.

Does the heater work right away or does it need calibration?

The heating element will operate immediately once power reaches it. No programming or setup required — just mount and go.

What if the motor or heater doesn't work after installation?

Test electrical function before final installation. If either component fails, inspect the door harness for corrosion or loose pins — common culprits in used OEM mirrors. Verify 12V power at the connector with a multimeter.