high pitch noise when car is turned on

[mojojojo]

Hi, when im using the car in accessory mode there are no high pitched noises but as soon as i turn the key to ON or START the car i can hear this high pitch noise from back speakers, i had disconnected the cables from the amplifer and it disappeared but came back once i plugged it back in. I have no clue on how i am able to fix this, anyone have ideas?

AMP : Pioneer GM-A4604
Speaker : Pioneer TS-A6965S
Car : 2011 Lancer

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[wew lad 5,000+ posts]

Clean your ground for the pioneer amplifier. Most likely a ground loop. Other possibilities are a bad headunit ground or an alternator on the way out.

 

[mojojojo]

Clean your ground for the pioneer amplifier. Most likely a ground loop. Other possibilities are a bad headunit ground or an alternator on the way out.

how to clean ground for amplifier?

 

[wew lad 5,000+ posts]

how to clean ground for amplifier?

Trace the large black wire back to where its grounded