Pinpoint Test E: Loud Popping Sound When Cycling The Ignition Switch

Information and Entertainment System

Pinpoint Tests

Pinpoint Test E: Loud Popping Sound When Cycling The Ignition Switch

Refer to Wiring Diagram Set 130, Audio System/Navigation for schematic and connector information. Diagrams By Number

Normal Operation

Voltage is supplied to the Audio Control Module (ACM) through circuit 1000 (RD/BK) when the ignition switch is turned to the START position. When the ACM receives this voltage, it mutes all speaker outputs and subwoofer amplifier enable circuits to eliminate the possibility of speaker pops during engine cranking.

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



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

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

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E1 CHECK CIRCUIT 1000 (RD/BK) FOR VOLTAGE


- Ignition OFF.
- Disconnect: ACM C290d.
- Disconnect: Starter Relay.
- Hold the key in the START position.
- Measure the voltage between the ACM C290d-15 circuit 1000 (RD/BK), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
GO to E2.

No
VERIFY the Smart Junction Box (SJB) fuse 20 (10A) is OK. If OK, REPAIR the circuit. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.

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E2 ISOLATE THE FRONT/REAR SUBWOOFERS


NOTE: Repeat this step for each subwoofer amplifier.

- Ignition OFF.
- Connect: ACM C290d.
- Disconnect: Suspect Subwoofer Amplifier.
- Cycle the key through all of the ignition switch positions.
- Is a loud popping sound present for only one subwoofer amplifier?

Yes
INSTALL a new subwoofer amplifier for the suspect subwoofer amplifier. REFER to Subwoofer Amplifier - Door Subwoofer Amplifier - Door or
Subwoofer Amplifier - Luggage Compartment Subwoofer Amplifier - Luggage Compartment. TEST the system for normal operation.

No
GO to E3.

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E3 CHECK FOR CORRECT ACM OPERATION


- Connect: Starter Relay.
- Disconnect all the ACM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the ACM connectors and make sure they seat correctly.
- Operate the system and determine if the concern is still present.
- Is the concern still present?

Yes
INSTALL a new ACM. REFER to Audio Control Module (ACM) Removal and Replacement. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

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