Test M: Loud Popping Sound When Cycling The Ignition

PINPOINT TEST M: LOUD POPPING SOUND WHEN CYCLING THE IGNITION

M1-M4:

M4-M5:

Normal Operation
Voltage is sent by the smart junction box (SJB), through circuit 1786 (BN/PK), to the audio unit when the ignition switch is turned to the START position. The audio unit then immediately mutes all speaker outputs and the subwoofer amplifier enable circuit output to eliminate the possibility of speaker pops during engine cranking.

Possible Causes
- Circuit 174 (YE) short to voltage
- Circuit 1786 (BN/PK) open
- Subwoofer amplifier
- Audio unit
- Smart junction box (SJB)