Steve 88

I have been trying to isolate/eliminate a constant static in my stock audio system. Last night I stumbled onto a strange symptom. When my headlights are turned on, the noise stops. Headlights off, noise returns.

I would kinda maybe understand if the noise started when the lights were on, but it's the reverse of that. I'm completely stumped. Any ideas?

Alan

How does the sound change when you turn on the rear windscreen defroster?

Try to figure out if its better when the loading on the alternator is higher from whatever source... or is it specifically just the headlights. If its any source - I'd say the alternator/regulator may have an issue.

is your audio system stock - as in never been touched - or stock as in returned to stock from something else ?

Alan

Steve 88

The rear defroster does not seem to affect the static. The sound might be interupted briefly when I turn the defroster on, but then it resumes.
The a/c did not affect it either. When I turn the headlights on, the static ceases immediately and does not return.

A very logical theory, though. Thanks, Alan.

The audio is original stock Blaupunkt.

auzivision

If the static is somewhat of a hum or whistle proportional to the RPMS, it could be a dirty ground somewhere introducing a slight voltage difference... a ground loop isolator ($15 @ Radio Shack) between your head unit and amp would eliminate this.

Ground is supposed to be ground the world around (or earth for those English folks), but unfortunately not all grounds are created equal. The fact that your head unit is grounded in one place and your amp in another can easily cause a slight difference. Even the slightest difference will be amplified through the speakers.

Perhaps the headlight on versus off is offsetting this difference in some way. If you don’t want to introduce non-stock items… you might concentrate on cleaning and conditioning all your grounds.

Steve 88

The static only begins when the engine starts, but it is not the traditional RPM-dependent whining. It is a steady crackling sound. I cleaned all ground points about a year ago, maybe it is time again.

Steve 88

Any other thoughts on this mystery? I am stumped.


Bump....................

Steve 88

Fixed! Finally! Thanks to everyone who offered ideas. I was trying to repair a wire to the Hall sensor when I came across a dangling wire. Turned out to be the passenger side coil ground.

No static... No static....No static at all..... (sounds like an old song).

Again, thanks to everyone.

Charley B

So now explain to me how turning on the headlights grounded the coil.

Steve 88

I can guess as to why the static was reduced at higher rpm, but I have no idea why the headlights affected it. This had plagued me for quite some time, so I am thrilled to have a solution.