I started in on my project to hardwire my dashcam into the M3 this weekend. After stripping much of the interior and getting it all wired in, I was extremely excited when I turned the ignition switch, and it worked! Then, I turned on the radio and it was filled with static. Turned off the ignition, and the static went away.
So the details are that I wanted to do this project the right way. No soldering onto existing connections and no splicing wires. I bought an add a fuse to tap into the circuit for the garage door (on only with ignition) and ran the wires along the A-pillar and behind the headliner.
The issue comes from the fact that the dashcam runs off of 5V which meant that I needed to install a 12V to 5V step down. I believe that it is the step down box itself that is causing the interference through the air. For some trouble shooting I brought in a standalone radio and it was interfered with as well.
So my questions are- Is there some sort of shielding that I can wrap it in to keep the interference from getting out? Could it be a flaw with this specific unit, or would another likely do the same thing? Is there any further troubleshooting I can do? The unit I bought is this one.