Audio System - Diagnostics: Pre-Check

IDENTIFICATION OF NOISE SOURCE
1. Identify the condition under which the noise occurs, and check the noise filter on the related part.
  
  Fig 1: Audio System Noise Occurs Condition & Source Table
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2. Reference:
  - Make sure first that there is no noise from outside. Failure to do so makes it difficult to detect the noise source and leads to misunderstanding.
  - The noise should be removed in descending order of loudness.
  - Setting the radio in a tuneless state makes it possible to notice the noises, which help to recognize the phenomena.