Pinpoint Test C: Loud Popping Sound When Cycling the Ignition Switch
Information and Entertainment System
Pinpoint Tests
Pinpoint Test C: Loud Popping Sound When Cycling The Ignition Switch
Refer to Wiring Diagram Set 130, Audio System for schematic and connector information. Diagrams By Number
Normal Operation
When the key is placed in START, voltage is sent to the audio unit through circuit 1000 (RD/BK). When the audio unit receives this signal, it mutes the subwoofer amplifier through circuit 173 (DG/VT). This prevents a voltage surge in the speaker circuits, which could result in a popping noise. After the key is removed from START, the audio unit directs audio signals to the speakers through separate positive and negative circuits.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Subwoofer amplifier
- Audio unit
PINPOINT TEST C: LOUD POPPING SOUND WHEN CYCLING THE IGNITION SWITCH
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 RECORDED DTCs
- Check the recorded DTCs.
- Are any DTCs retrieved?
Yes
For DTC B2913, Go To Pinpoint Test D. Pinpoint Test D: the Subwoofer Is Inoperative
For all others, REFER to DTC Charts. [1][2]Diagnostic Trouble Code Descriptions
No
GO to C2.
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C2 CHECK THE AUDIO UNIT START INPUT CIRCUIT FOR VOLTAGE
- Ignition OFF.
- Disconnect: Starter Relay.
- Disconnect: Audio Unit C290a.
- Start the engine.
- Measure the voltage between the audio unit C290a-15, circuit 1000 (RD/BK), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to C3.
No
VERIFY the Central Junction Box (CJB) fuse 3 (10A) is OK. If OK, REPAIR the circuit. 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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C3 SUBSTITUTE THE SUBWOOFER AMPLIFIER
- Ignition OFF.
- Connect: Audio Unit C290a.
- Install a known good subwoofer amplifier.
- Ignition ON.
- Operate the audio unit in radio tuner (AM/FM) mode.
- Does the system operate correctly?
Yes
INSTALL a new subwoofer amplifier. REFER to Subwoofer Amplifier Service and Repair. TEST the system for normal operation.
No
INSTALL the original subwoofer amplifier. INSTALL a new audio unit. REFER to Audio Unit Service and Repair. TEST the system for normal operation after the repair.
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