Relay Buzzing

okay.... where do I begin.

First off, I'm female!      T-T

Second, here is the situation.

The relay is switching the domelight wire to be a 12+ when needed. However when the lights fade, the relay buzzes.

Wizard, I thank you for the diagrams, but I have no idea what they mean.

minna tasukette!

Above diagram is a picture of what "Ween" suggested.   His idea, my picture.

Simply add the capacitor and the diode to your relay.  As ween stated, make sure you polarize the capacitor properly.  The Diode must go on the positive wire.  The banded end of the diode needs to be connected to the relay. 

When the vehicle drops the voltage to fade the lamp, the cap will keep the relay energized for a second or so.  The diode keeps the stored cap voltage from going back into the vehicle. 

Oops, I was just playing the percentages there, and lost-

I guess the question I should ask is,  what is the output of the relay being used for?  It sounds like you're not driving the domelight with the relay, because the Ion's doing that, with its dimmer control.  If you simply need an inverted signal from the negative switching dome light control to trigger an alarm or something low current like that, you could use one of the circuits Hotwaterwizard to invert it from (-) to (+).   As long as it doesn't matter that the (+) signal will have a rapid oscillation during the dimming time, it should work well enough.

But, if you're using the relay to drive lights or something needing a good amount of power, then the relay would serve the purpose, and you could try something along the lines of adding Ween's cap and diode as I am an idiot pictured.