Pinpoint Test C: Poor Quality/Distorted/No Sound From One Or More Speakers (Not All Speakers)

Information and Entertainment System

Pinpoint Tests

Pinpoint Test C: Poor Quality/Distorted/No Sound From One Or More Speakers (Not All Speakers)

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

Normal Operation

The audio unit directs the audio signals to the speakers through separate positive and negative circuits for each of the 4 audio channels: LH front, RH front, LH rear, and RH rear. The audio unit provides internal circuit protection for shorts to ground, shorts to voltage, and shorts between any output circuits.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- Speaker
- Audio unit

PINPOINT TEST C: POOR QUALITY/DISTORTED/NO SOUND FROM ONE OR MORE SPEAKERS (NOT ALL SPEAKERS)

NOTICE: For the CD6 audio unit, the audio unit must be placed in shipment mode before removal. Refer to Audio Unit Shipment Mode. Failure to follow this instruction may result in damage to the audio unit. Audio Unit Shipment Mode

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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C1 CHECK THE AUDIO SIGNAL TO THE SUSPECT SPEAKER

NOTE: The AM/FM audio unit only has front door-mounted speakers.

- Ignition OFF.
- Disconnect: Suspect Speaker.
- Ignition ON.
- Operate the audio unit in radio tuner (AM/FM) mode.
- Measure the AC voltage between the suspect speaker pin 1 and pin 2, harness side as follows:









- Is a fluctuating AC voltage present?

Yes
INSTALL a new speaker for the suspect speaker. REFER to Speaker - Door Service and Repair. TEST the system for normal operation.

No
GO to C2.

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C2 CHECK THE SPEAKER CIRCUITS FOR A SHORT TO VOLTAGE

- Ignition OFF.
- Disconnect: Audio Unit C290a.
- Ignition ON.
- Measure the voltage between the suspect speaker, harness side and ground as follows:









- Is any voltage present?

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

No
GO to C3.

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C3 CHECK THE SPEAKER CIRCUITS FOR AN OPEN OR SHORT TO GROUND

- Ignition OFF.
- Measure the resistance between the audio unit, harness side and the suspect speaker, harness side; and between the audio unit, harness side and ground as follows:









- Are the resistances less than 5 ohms between the audio unit and the suspect speaker, and greater than 10,000 ohms between the audio unit and ground?

Yes
INSTALL a new audio unit. REFER to Audio Unit Audio Unit. TEST the system for normal operation.

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

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