I just purchased a 2009 Honda Accord EX-L and would like to wire an LED strobe light bar (the Knight Rider type) that automatically comes on when the car is turned off or better yet - integrated with the alarm system. I want to mount it behind the rear view mirror so that it is clearly visible. Does anyone know how I would go about this and/or connecting it to power that is active only when the vehicle is off? The instructions state something about hooking it up to a radio fuse, but isn't that OFF when the car is off?

I'd rather not tear half the dash and everything apart for something so small. It would look really cool though. Any help appreciated.

It looks like sort of like this: http://westcoastpromoman.com/catalog..._light_bar.jpg

 

I don't know any of the wiring details for 2009, but even my 2003 had computer data-bus connections between lots of components. Traditionally, the radio has switched power, but ALSO has continuous power to maintain it's memory & stored station presets.

I don't know of any power source that's live ONLY when the car is switched off. Stuff like the radio have their own logic that compares the switched power & the unswitched power.

 

find a wiring diagram before you try anything.

 

Do you know who has a wiring diagram? Do I have to fork out for the whole service manual from Honda?

 

Helm, Inc. makes a service manual, probably around $70 and the best in the business. It should have a wiring diagram for everything, not just the necessities like Haynes/Chiltons. Definitely a good investment.