Possible ground issue?

I think everyone's missing an important point - it worked before the APU was messed with. If any of you worked on APUs you will understand that if there in electrical issues with the unit, it can become one with the rest of the truck. In this case, there is a good chance that changing the power source to something else but what if the problem causes the AM radio the same issue?

I am thinking the best thing to do is ask what was done to the APU to cause a change, power cables being changed is one because not a lot of these techs are actual techs but part's changers who went to school to learn a limited amount of information to get by and that's it. Ask them to explain how the control board works and most of them are dumbfounded and could not answer it.

 

No, this is totally different issue, but certainly get the mic fixed or replaced.

 

Pete did ya by any chance hit the gas pedal on that video ? Is so that's the alternator noise coming in through the electrical lines.

 

I'm looking a possible loose ground on the apu. Pete I would try the noise filter and if it doesn't fix that then you might try tightening up the connections on the APU and batteries.

 

You should use a 4 wire filter not 3 wire since common mode noise on the ground side is unfiltered with a three wire type. Since you are stuck with it, black is ground. Red is power in, blue is power going to the radio. Simple Pi filter where the power going in is filtered, coming out the blue wire. I would have thought this was marked on the package.

I should add: "should i just plug the blue one into the black stud?" Only if smoke is your goal.