Quick Door Front Panel Question

[Skyline]

I took the driver's door panel off to change the front mid-bass drivers. There's an orange plug-in bulb, (connected to a pair of wires) that wasn't inserted anywhere. It lights up when the headlights are on. Where does that go?

I should mention that it looks like the window/mirror control panel was swapped at some point as it's got a mirror fold button, (an option I don't have one the car). The control panel is already illuminated. Was the orange bulb used with an older panel and no longer needed, or does it go elsewhere?