2008 Fusion - pop in speakers when brake applied

Has anyone had this problem? You get a "pop" noise in the speakers with the radio on FM and you put on the brake. Volume has to be in the 2 to 3 bar range to hear the noise.
Fred
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[This followup was posted to alt.autos.ford and a copy was sent to the cited author.]
says...

Your stoplamp switch may be going bad and arcing, causing some RF noise. It should also do it on AM. Does it happen with a CD or aux input?
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I don't usually listen to anything other than FM, but I'll see if it happens in the other modes. The car did this since new but I thought it was a mechanical noise all this time until I did some trips with the radio off and I didn't hear the noise.

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Surely the car must still be covered under the 36,000 mile B to B warranty????

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I doubt that this is covered under the warranty.

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Why?

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| >>> says... | >>>> Has anyone had this problem? | >>>> You get a "pop" noise in the speakers with the | >>>> radio on FM and you put on the brake. Volume | >>>> has to be in the 2 to 3 bar range to hear the noise. | >>> | >>> Your stoplamp switch may be going bad and arcing, causing some RF noise. | >>> It should also do it on AM. Does it happen with a CD or aux input? | >>> | >>> -- | >>> If there is a no_junk in my address, please REMOVE it before replying! | >>> All junk mail senders will be prosecuted to the fullest extent of the | >>> law!! | >>> http://home.att.net/~andyross | >>
The "pop" most certainly is RF noise. Here is what's happening.
The wire that is plugged into the stop light switch is too close to the positive wire for the radio. The "pop" that you hear is the change in the electromagnetic field in the stop lamp circuit.
There are two solutions to the problem.
First and best is to find the circuit going to the stop lamp switch, follow it up the harness and verify that it is located in the same harness are the radio power wire. If you find that to be true, moving the stop lamp wire away from the radio circuit wire about a inch will stop the pop you hear in the radio.
Second, if you can't locate the wire or find that the stop lamp circuit is not in close proximity to the radio circuit, a Pi filter should be installed in the positive wire leading to the radio. A Pi filter is the fancy name for an RF filter because the electronic diagram resembles the math symbol for the constant Pi (3.1415926...). Electronic symbol resembles this character (?).
The RF filter has an induction coil and a capacitor. Without going into details about how it works, the capacitor allows AC voltage to pass to ground while blocking DC. Thus, the errant AC (RF) current passes harmlessly to ground thereby eliminating the pop before you hear it in the speakers.
The Pi filter has THREE LEADS. Two heavy leads (the input and output positive leads) and one thinner lead which is attached to a ground.
Just follow the directions that comes with the filter and the "pop" will be gone. But first, try to find the wire and move it. It's known as induction since the AC magnetic field "induces" the current into another adjacent circuit.
You can purchase a Pi (RF) filter at any radio shack (or at least Radio Shack used to have them).
I hope this helps!
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Steve Spence
Independent AMSOIL Dealer
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| |
Sorry about the question mark (?). I guess that this text only medium does not support extended ASCII characters that I had in my text before I sent it along through the internet..
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