How to Remove an Alternator Whine From a Car Stereo

by Tara Kimball
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Alternator whine in your car stereo can be an elusive problem. As the RPMs of your vehicle rise, the volume of the alternator whine can increase as well. Identify the underlying cause of the whine to silence it for good. There are several possible causes of alternator whine and troubleshooting is the best way to isolate it. If proper grounding and wire placement does not eliminate the noise, a filter may be the ultimate resolution.

Step 1

Check the wire routing for your car stereo. The RCA wires should run on the opposite side of the car from the power wires. Run the RCA lines on the driver side of the vehicle and the power lines on the passenger side of the vehicle for the best noise reduction.

Step 2

Use a digital multimeter to read the voltages from the lines connecting to the battery, the radio and the amplifiers. Connect one of the multimeter leads to the ground line feeding into each unit and the other lead to the power line feeding into the unit. If there is a difference of over one-half of a volt between the readings, you may need to adjust the grounds in your audio system.

Step 3

Ground your amplifiers before grounding any other components. Make sure that you ground each amplifier independently, ideally at the rear of the car. Ground the stereo system at the front of the vehicle away from the battery. When grounding the amplifiers and stereo, run the ground wire from the component to a bare metal point on the car. Run a screw or bolt through the loop on the ground wire and tighten it securely.

Step 4

Install a noise filter in the power line between the alternator and the battery. Connect the line from the battery into the battery-side terminal of the filter. Connect the line from the alternator into the alternator-side terminal of the filter.

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