I disconnected the antenna at the radio as well as unscrewed the antenna from the mount. On both occasions, the noise disappeared. I also temporarily rerouted the wires away from the brake mechanism and the noise remained. I am convinced it is coming from the brake booster at this point. But, it seems to be originating from the antenna rather than the power. Maybe I can find an RFI filter for the antenna somewhere or try another antenna.
I did find a ferrite snap on choke for the coax at Radio Shack
http://www.radioshack.com/product/in...032058.2032230 and thought that would be an inexpensive attempt to solve the problem.