Test C: Loud Popping Sound When Cycling The Ignition Switch

PINPOINT TEST C: LOUD POPPING SOUND WHEN CYCLING THE IGNITION SWITCH

Normal Operation
When the key is placed in START, voltage is sent to the audio unit through circuit 1000 (RD/BK). When the audio unit receives this signal, it mutes the subwoofer amplifier through circuit 173 (DG/VT). This prevents a voltage surge in the speaker circuits, which could result in a popping noise. After the key is removed from START, the audio unit directs audio signals to the speakers through separate positive and negative circuits.

This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Subwoofer amplifier
- Audio unit

C1-C3: