Pinpoint Test D: The Audio Unit Illumination Is Inoperative

Instrument Cluster and Panel Illumination

Pinpoint Test D: The Audio Unit Illumination Is Inoperative

Refer to Wiring Diagram Set 71, Cluster and Panel Illumination for schematic and connector information. Diagrams By Number

Normal Operation

With the parking lamps on, the Lighting Control Module (LCM) supplies a variable Pulse Width Modulated (PWM) voltage to the audio unit on circuit 484 (OG/BK). The base audio unit illumination is grounded through circuit 57 (BK). The dual media audio unit is grounded through circuit 694 (BK/LG).

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- Audio unit



PINPOINT TEST D: THE AUDIO UNIT ILLUMINATION IS INOPERATIVE

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 CIRCUIT 484 (OG/BK) FOR AN OPEN


- Disconnect: Audio Unit C290a or C240.
- With the parking lamps on, rotate the instrument panel dimmer switch to the maximum brightness position.
- Measure the voltage between the audio unit C290a-3, circuit 484 (OG/BK), harness side and ground; or between the audio unit C240-1, circuit 484 (OG/BK), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
GO to D2.

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

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D2 CHECK CIRCUIT 57 (BK) OR CIRCUIT 694 (BK/LG) FOR AN OPEN


- Disconnect: Negative Battery Cable.
- Measure the resistance between the audio unit C290a-13, circuit 694 (BK/LG), harness side and ground; or between the audio unit C240-2, circuit 57 (BK), harness side and ground.




- Is the resistance less than 5 ohms?

Yes
REMOVE the audio unit. SEND it to an authorized audio system repair facility. TEST the system for normal operation after repair.

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

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