We can ignore the Multi-Remote Control Relay for now, as it is not present in some models.
In one model, Smart Entrance Control Unit is placed behind the meter panel(hooked to the meter cluster). And in the other model unit is placed somewhere near to the AC Filter in the passenger side.
But I think you don't have to locate the unit to check whether it is functioning.
Go inside the car, lock all doors (using the driver side lock).
Insert the key into the key cylinder and remove it from the cylinder six times or more within 10 seconds.
Then door locks should unlock. If so, we can say that your Receiver is functioning.
You may have to try several times as this has to be done in the correct speed.