Alternator whine in stereo.

[Colt45ws]

My CVPI has a lot of whine in the stereo. It sounds like a supercharger when I turn it up.
Heres the thing though.
Its dead stock.

On my LX, I have a aftermarket headunit along with an amplifier, so I get some noise due to an imbalance somewhere. I actually get injectors ticking on that one, not so much alternator noise. Havent figured that one out yet.

But, back to the CVPI, it has stock ford tape deck with stock ford speakers and it whines. Trying to figure out what it could be. Any ideas.

 

[Donald]

Add a capacitor.

 

[apwillard1986]

Ground fault?

 

[Win]

In my experience, alternator whine on a stock car is a bad battery, or a bad alternator, or a ground point that has gone marginal with age and needs cleaning, probably the latter.

If aftermarket equipment is involved, it's a ground loop causing the whine.

 

[SuzukiGoat]

Ford is notorious for running wiring every which way with little concern for how they will look in 20 years.

Easiest solution...aftermarket wiring to speakers routed correctly. But even that might not fix it.

A new headunit with a proper ground, new quality properly run wiring, and new properly mounted speakers.

I've always run a ground strap to the interior from the battery and then hook small accessories to it.

Lay a voltage meter.on your radio ground and see what you get with alternator engaged...Stranger things have happened.

 

[UNC017]

One blown diode in the alternator will really create an audio whine since the voltage ripple increases drastically.

 

[The_Jeff]

Are the rear speakers wired in the same channel (kick panel?) as the fuel pump wiring? Could be picking up a diode whine that way.

 

[Colt45ws]

I was messing with it just now, and discovered the problem may be in the factory radio. I had it pulled out and when I moved it around it would randomly shutoff. So I started playing with the wiring thinking it was a broken wire, but couldnt reproduce. At one point, I grabbed the case to move it and it immediately shut off.
I let go and it came back on.
Squeezed the case and it shut off.
Keep in mind, Im not really putting the hurt on it, either. Just the normal amount of force one would use to grab and install a radio.
So, Ill have to replace the radio before I can try tracking this down again. I just ordered the vehicle side harness that matches my LX so I can put the factory radio I pulled out of it in the CVPI. Thankfully someone installed the 2003+ dash vent duct in it so I can use a true double DIN like it is.

 

[meep]

sounds like you found it.

diode in the alt, as suggested above, was my next suggestion.

fyi-- capacitors smooth ripple but do not block it. inline power filters usually have a combination of a capacitor AND an inductor (coil of wire). inductor blocks fluctuations above a given frequency. Caps smooth out the V, but not completly.

isolated über ground as described above is also a very good way to go.

 

[The_Jeff]

Take apart your old radio and look for half busted solder traces. Won't cost you anything and might fix it. Look where pins are soldered to circuit boards.