I install;ed my system last week and have not been having any problems. Today I opened the dash up again to go ahead and run a wire from the illumination wire on the unit over to my headlight switch (2006 VW rabbit) b/c there is no illumination wire that runs to the factory HU. The unit now dims like it is supposed to when I turn on my headlights however, as soon as I flip on my headlights my sub begins to hum. The humming is very quiet and only noticable without the engine running. The hum stops as soon as I turn off the headlights. Any ideas?

I had the same problem with my 06 civic. When I turned on my headlights the subs would hum. It turned out that it was the RCA cable to the sub amp was touching ground behind the radio. Try removing the radio and make sure you wrap the RCA's with black electrical tape.

Why's it gotta be black e-tape. I've never had a problem using yellow, white, blue, or green.

the thought of having to take the whole unit out again = ignoring the humming. argh