Did you or did you not have an AUD under the passenger seat from factory?
If you did not have the AUD but you have the harness unplugged, this means your IHU drives the speakers and the harness under the seat is not connected. You will need to rewire from the connector to the doors.
If you had the AUD from factory, what is the original part number and the new one? what is your model / year and the donor car's model / year?
Send a picture of the connectors under the passenger seat.
You will need multimeter and an external audio source for testing and determining which pin goes to where.
If you provide your VIN number I might be able to check on VIDA to see what you have.
If you did not have the AUD but you have the harness unplugged, this means your IHU drives the speakers and the harness under the seat is not connected. You will need to rewire from the connector to the doors.
If you had the AUD from factory, what is the original part number and the new one? what is your model / year and the donor car's model / year?
Send a picture of the connectors under the passenger seat.
You will need multimeter and an external audio source for testing and determining which pin goes to where.
If you provide your VIN number I might be able to check on VIDA to see what you have.