Pinpoint Test A: The Audio Unit Is Inoperative/Does Not Operate Correctly

Information and Entertainment System

Pinpoint Test A: The Audio Unit Is Inoperative/Does Not Operate Correctly

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

Normal Operation

The audio unit receives voltage at all times through circuit 1772 (VT), and voltage in RUN or ACC through circuit 964 (DB/LG). The audio unit receives ground through circuit 694 (BK/LG).

This pinpoint test is intended to diagnose the following:

- Fuse
- Wiring, terminals or connectors
- Audio unit



PINPOINT TEST A: THE AUDIO UNIT IS INOPERATIVE/DOES NOT OPERATE CORRECTLY

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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A1 CHECK THE OPERATION OF THE AUDIO UNIT


- Ignition ON.
- Operate the audio unit in radio tuner (AM/FM) mode.
- Is the audio unit display illuminated?

Yes
GO to A2.

No
GO to A4.

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A2 CHECK FOR SOUND COMING FROM THE AUDIO UNIT SPEAKERS


- Carry out the speaker walk-around test. Inspection and Verification
- Verify that sound is coming from the speakers.
- Is there sound coming from the speakers?

Yes
GO to A3.

No
INSTALL a new audio unit. REFER to Audio Unit Service and Repair. TEST the system for normal operation.

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A3 CHECK THE CONTROLS AND FEATURES


- Refer to the Owner's Literature for audio system controls.
- Verify that all the controls and features operate correctly.
- Do all the controls and features operate correctly?

Yes
The system is operating correctly at this time.

No
INSTALL a new audio unit. REFER to Audio Unit Service and Repair. TEST the system for normal operation.

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A4 CHECK THE VOLTAGE TO THE AUDIO UNIT


- Ignition OFF.
- Disconnect: Audio Unit C290a (Except Base).
- Disconnect: Audio Unit C240 (Base).
- Ignition ON.
- For all vehicles except base, measure the voltage between the audio unit C290a-1, circuit 1772 (VT), harness side and ground; and between the audio unit C290a-2, circuit 964 (DB/LG), harness side and ground.




- For vehicles with base audio, measure the voltage between the audio unit C240-9, circuit 1772 (VT), harness side and ground; and between the audio unit C240-10, circuit 964 (DB/LG), harness side and ground.




- Are the voltages greater than 10 volts?

Yes
GO to A5.

No
VERIFY the Central Junction Box (CJB) fuse 9 (7.5A) or fuse 12 (15A) is OK. If OK, REPAIR the circuit in question. 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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A5 CHECK THE AUDIO UNIT GROUND CIRCUIT FOR CONTINUITY


- Ignition OFF.
- For all vehicles except base, measure the resistance between the audio unit C290a-13, circuit 694 (BK/LG), harness side and ground.




- For vehicles with base audio, measure the resistance between the audio unit C240-11, circuit 694 (BK/LG), harness side and ground; and between the audio unit C240-16, circuit 694 (BK/LG), harness side and ground.




- Are the resistances less than 5 ohms?

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

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

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