Pinpoint Test E: The Audio Unit Illumination Is Inoperative

Instrument Cluster and Panel Illumination

Pinpoint Tests

Pinpoint Test E: 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.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- Audio unit

PINPOINT TEST E: 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, Mounting and Cables Battery Disconnect.

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E1 CHECK THE ACM INPUT CIRCUIT 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 C240-1 (base audio), circuit 484 (OG/BK), harness side and ground; or between the audio unit C290a-3 (Sanyo audio), circuit 484 (OG/BK), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
GO to E2.

No
REPAIR circuit 484 (OG/BK) for an open. TEST the system for normal operation.

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E2 CHECK THE ACM GROUND CIRCUIT FOR AN OPEN


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




- Is the resistance less than 5 ohms?

Yes
REMOVE the audio unit. REFER to Information and Entertainment Systems Service and Repair. SEND it to an authorized audio system repair facility. TEST the system for normal operation after repair.

No
REPAIR the ground circuit for an open. TEST the system for normal operation.

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