f 350 diesel severe interference

The vehicle: 2001 Ford F-350 Super Duty Diesel 7.2ltr The System: Pioneer AVIC-f700BT Rockford fosgate amps, 2ch and a 4ch and a .5f cap The problem: this problem started when i was installing an starter kill switch using the wires at the ignition harness. i was testing the switch so i was cycling the ignition. i turned the truck off then to run and had a significant amount of interference that hadnt been there just a few moments ago. here's what ive done so far to narrow down the problem: regrounded the head unit checked amp grounds. good ran rca directly to the amp, still buzzed. there is absolutely no interference in ACC, only in RUN i pulled the radio fuse and the buzzing still existed so i started pulling fuses until the buzzing sound went away and i found that the circuit causing the interference is 30amp fuse that controls the fuel heater, wastegate solenoid, and the injector driver module relay. This is all diesil only equipment. i pulled out the injector driver relay and that eliminated half of the interference but not all of it. i dont know what the wastegate is and the fuel heater im assuming isnt active because it's a warm day. also, when the 30 amp fuse is pulled the wait to start light doesn't come on. the sound doesn't seem to be following anything as far as i can see. when the truck is running turning on the AC or anything else that draws a lot of power changes the tone of the interference. so this is where i'm at now, i tried disconnecting the kill switch and checked all the wiring and its fine so i know its not the kill switch. i dont know what to do next... any help at all would be greatly appreciated, i think my client is scared i really messed something up do i want to get it fixed asap!

So it does this with the truck off...But in run position...? Or only w/ truck running?M.E.C.P & First-Class

Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!

Okay heres what it sounds like, in the video it's a lot louder than it actually is. annoying interference

in acc mode: no interference off position : no interference in run w/truck running or not running: it makes the buzzing sound

Hey everybody, it happened again.  I wish I knew what was causing it.  It must be IE8's invisibility function.  Does anyone know how to defeat it?

are you saying this is a common problem?

i dont think it's the head unit because it still makes the noise even when the radio fuse is not installed in the fuse box