Pinpoint Test L: Poor Quality/Distorted/No Sound From All Speakers - All Audio Systems Except THX(R)

Information and Entertainment System

Pinpoint Tests

Pinpoint Test L: Poor Quality/Distorted/No Sound From All Speakers - All Audio Systems Except THX(R)

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

Normal Operation

When the key is in START, the Audio Control Module (ACM) receives voltage on the START signal circuit. The ACM then mutes the speaker output to prevent voltage spikes from producing a popping noise through the speakers. However, a short to voltage on this circuit causes the ACM output to be continuously muted.

If a speaker circuit fault DTC is set in the ACM, the cause of the concern is a short to ground or short to voltage in an individual speaker circuit, which has caused the ACM overload protection to activate. If a speaker circuit fault DTC is present, refer to DTC Charts. [1][2]Diagnostic Trouble Code Descriptions

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- ACM



PINPOINT TEST L: POOR QUALITY/DISTORTED/NO SOUND FROM ALL SPEAKERS - ALL AUDIO SYSTEMS EXCEPT THX(R)

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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L1 CHECK THE START SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE


- Ignition OFF.
- Disconnect: ACM C240a.
- 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 L2.
.

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L2 CHECK FOR CORRECT ACM OPERATION


- Ignition OFF.
- 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) 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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