Alternator whine

[Cheburashka]

I installed a new head unit and now I have alternator whine/ground loop noise.

There may be an issue as I have the premium sound system on my 1995, so I took amp out from the deck and sent it to the factory amp. Essentially, I am using 2 amps..

I wonder if that is the problem and if bypassing that second amp would solve that. Does anyone know if a bypass harness exists for a 1995 amp?

 

[RonD]

So you can hear this noise thru the speakers, and you think its coming from alternator or spark plugs?

Or you can hear the alternator making a noise in the engine bay with hood up and engine running?

 

[Cheburashka]

It's through the speakers. I think alternator whine is the correct term for it.

Basically a static noise that changes to a higher pitch with higher RPM.

I think it could be these things:
Something to do with separate grounds of the amp and the head unit

Something to do with the fact that I'm essentially running two inline amps

Something to do with the fact that I'm running amplified signal over preamp wiring to the amp

 

[RonD]

Wait a minute
"I'm running amplified signal over preamp wiring to the amp"

???

You are running 2 amplifiers in series?

Music---amp-----amp------speakers

Thats a no-no

Remove either amp
There is no "ground" issue

 

[Cheburashka]

Yup exactly, in series.

The amp on 95+ is in a terrible location.

I guess the Ford engineers decided in 95 that the amp and heater core are too accessible and made sure they are as hard to reach as possible.

I'll try to eliminate the factory amp without removing the entire interior panel. I looked for an adapter to eliminate the amp but couldn't find anything.

 

[RonD]

The speaker wires should be in the kick panels, cut and splice

Wire colors for 1995 here: https://www.therangerstation.com/tech_library/pdf_documents/1995_Ranger_Premium_Radio_Wiring.pdf

 

[pjtoledo]

easy to isolate and determine if it's alternator whine. disconnect the alternator and run on just the battery for a few seconds.