Pinpoint Test D: Poor Quality/Distorted/No Sound From All Speakers - Audiophile

Information and Entertainment System

Pinpoint Tests

Pinpoint Test D: Poor Quality/Distorted/No Sound From All Speakers - Audiophile

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

Normal Operation

When the ignition is in the START position, voltage is supplied to the Audio Control Module (ACM) through the start mute circuit. When the ACM 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 continually mutes the audio output, resulting in no sound from all speakers.

The audio amplifier and subwoofer amplifier each have their own enable circuit. However, they share a common ground. If the ground is open at the connection to the vehicle, neither amplifier can function.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- ACM



PINPOINT TEST D: POOR QUALITY/DISTORTED/NO SOUND FROM ALL SPEAKERS - AUDIOPHILE

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

NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.

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D1 CHECK THE START SENSE CIRCUIT FOR A SHORT TO VOLTAGE


- Ignition OFF.
- Disconnect: ACM C240a.
- Ignition ON.
- Measure the voltage between the ACM 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 D2.

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D2 CHECK THE AMPLIFIER GROUND CIRCUIT FOR AN OPEN


- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Disconnect: Subwoofer Amplifier C466a.
- Measure the resistance between the subwoofer amplifier C466a-2, circuit GD149 (BK/GY), harness side and ground.




- Is the resistance less than 5 ohms?

Yes
GO to D3.

No
REPAIR the circuit. TEST the system for normal operation.

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D3 CHECK FOR CORRECT ACM OPERATION


- Ignition OFF.
- Connect: All Disconnected Connectors.
- Disconnect all the ACM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect 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) 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.

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