Pinpoint Test C: Poor Quality/Distorted/No Sound From All Speakers

Information and Entertainment System

Pinpoint Test C: Poor Quality/Distorted/No Sound From All Speakers

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

Normal Operation

When the ignition is in the START position, a start input voltage is supplied to the Audio Front Control Module (ACM) from the Smart Junction Box (SJB). When the ACM (Audio Front Control Module) receives this voltage, it mutes the speaker output to prevent popping in the speakers as a result of voltage spikes during engine cranking, However, if there is a short to voltage on this circuit, the ACM (Audio Front Control Module) continually mutes the audio output, resulting in no sound from all speakers.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- ACM (Audio Front Control Module)

PINPOINT TEST C : POOR QUALITY/DISTORTED/NO SOUND FROM ALL SPEAKERS

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

C1 CHECK THE START SENSE CIRCUIT FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Disconnect: ACM (Audio Front Control Module) C240A.

- Ignition ON.

- Measure the voltage between the ACM (Audio Front Control Module) C240A-15, circuit CBP28 (GY/VT), harness side and ground.





Is any voltage present?

Yes
REPAIR the circuit. TEST the system for normal operation.

No
GO to C2.

C2 CHECK FOR CORRECT ACM (Audio Front Control Module) OPERATION

- Ignition OFF.

- Disconnect all the ACM (Audio Front Control Module) connectors.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect all the ACM (Audio Front Control Module) 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 (Audio Front Control Module). REFER to Audio Control Module (ACM) . 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.