[wagonman76]

You could tape some light gauge wire (light enough to not hinder the movement of the grille block, like maybe thin am/fm antenna wire) to both the spoiler and the grille block. Make sure the wires will easily touch when the grille block is closed. Maybe even use a small spring on one of the wires and tape the spring to the spoiler, like what is in the end of a battery case, that way the grille block won't have to be firmly bottomed out. Then run the wires to your dash, and connect them with an LED and appropriate size battery. The LED will come on when the grille block is closed.