Test D: Loud Popping Sound When Cycling The Ignition

PINPOINT TEST D: LOUD POPPING SOUND WHEN CYCLING THE IGNITION

Normal Operation
Voltage is sent through the start input circuit CBP28 (GY/VT) to the audio unit with the key in START. Upon receiving this signal, the audio unit mutes all speaker outputs to eliminate the possibility of speaker pops during engine cranking.

For the Audiophile audio system, the audio unit disables the subwoofer while the key is in START by keeping the enable signal below 0.4 volts.

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

D1:

D1-D2: