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

Information and Entertainment System

Pinpoint Tests

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

Refer to Wiring Diagram Set 130 (Fusion/Milan/MKZ, Fusion Hybrid/Milan Hybrid), Audio System/Navigation for schematic and connector information. Diagrams By Number

Normal Operation

The Audio Control Module (ACM) directs audio signals to the audio amplifier and to the subwoofer amplifier in the form of an AC voltage. The amplifiers boost the audio signals and send them to the speakers. The ACM provides internal circuit protection for shorts to ground or shorts to voltage.

A short to ground or short to voltage in the circuitry to one of the speakers may cause multiple speakers to lose sound due to the built-in overload protection feature of the ACM. In this case, a speaker fault DTC sets, and this pinpoint test should be followed to isolate the damaged circuit.

The speaker walk test can be used to isolate a concern with a particular speaker. This can reduce the diagnostic steps necessary to isolate the concern. To carry out the speaker walk test, refer to Audio Control Module (ACM) Self-Diagnostic Mode Audio Control Module (ACM) Self-Diagnostic Mode.

To enable the amplifiers, the ACM sends voltage through individual enable/clip circuits. The circuits act as both an output (to enable the amplifier) and an input (to detect an overload condition). The voltage sent by the ACM passes through a variable resistor in each amplifier, then to ground. As the amplifier reaches maximum output, the resistance in the variable resistor decreases. This decreases the voltage drop, resulting in the ACM detecting a higher voltage on the enable/clip circuit. When the voltage reaches the clip threshold, the ACM clips the audio output signal to the amplifier (heard as distortion), in order to prevent damage to the amplifier and speakers.

The enable/clip status is based on the following voltages, as detected by the ACM:

- Less than 0.4 volt: amplifier disabled
- Between 3.8 and 6.7 volts (nominal): amplifier enabled
- Greater than 8.5 volts: amplifier clipped

An open in the enable/clip circuit causes the speakers powered by that particular amplifier to produce no sound because the enable signal does not reach the audio amplifier. A short to ground or short to voltage can cause severe distortion to be heard in the speakers.

B1A01-B1A06:

This pinpoint test is intended to diagnose the following:

- Fuse
- Wiring, terminals or connectors
- Speaker
- Audio amplifier
- Subwoofer amplifier
- ACM

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

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 DETERMINE THE INOPERATIVE SPEAKER(S)

- Carry out the speaker walk test. Refer to Audio Control Module (ACM) Self-Diagnostic Mode Audio Control Module (ACM) Self-Diagnostic Mode.
- Is the concern only with the subwoofer speakers?

Yes
GO to D2.

No
If the concern is only with a tweeter speaker, GO to D14.

For all other concerns, GO to D17.

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D2 DETERMINE THE INOPERATIVE SUBWOOFER

- Operate the audio system in radio tuner (AM/FM) mode and observe the subwoofer operation.
- Do both of the subwoofers have a concern?

Yes
GO to D3.

No
GO to D11.

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D3 CHECK THE SUBWOOFER AMPLIFIER VOLTAGE SUPPLY

- Ignition OFF.
- Disconnect: Subwoofer Amplifier C466a .
- Measure the voltage between the subwoofer amplifier C466a-5, circuit SBP38 (BN/RD), harness side and ground.

- Is the voltage greater than 10 volts?

Yes
GO to D4.

No
VERIFY the Smart Junction Box (SJB) fuse 38 (20A) is OK. If OK, REPAIR the circuit. CLEAR any DTCs present. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short Diagrams By Number.

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D4 CHECK THE SUBWOOFER AMPLIFIER GROUND CIRCUIT FOR CONTINUITY

- Disconnect: Negative Battery Cable .
- Measure the resistance between the subwoofer amplifier C466a-2, circuit GD148 (BK/YE), harness side and ground.

- Is the resistance less than 5 ohms?

Yes
GO to D5.

No
REPAIR the circuit. CLEAR any DTCs present. TEST the system for normal operation.

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D5 CHECK THE SUBWOOFER AMPLIFIER ENABLE CIRCUIT FOR CORRECT VOLTAGE

- Connect: Negative Battery Cable .
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the voltage between the subwoofer amplifier C466a-1, circuit SME23 (VT/RD), harness side and ground.

- Is the voltage between 3.8 and 6.7 volts?

Yes
GO to D8.

No
GO to D6.

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D6 CHECK THE SUBWOOFER AMPLIFIER ENABLE CIRCUIT FOR A SHORT TO VOLTAGE

- Ignition OFF.
- Disconnect: ACM C240d .
- Ignition ON.
- Measure the voltage between the subwoofer amplifier C466a-1, circuit SME23 (VT/RD), harness side and ground.

- Is any voltage present?

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

No
GO to D7.

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D7 CHECK THE SUBWOOFER AMPLIFIER ENABLE CIRCUIT FOR AN OPEN OR SHORT TO GROUND

- Ignition OFF.
- Measure the voltage between the subwoofer amplifier C466a-1, circuit SME23 (VT/RD), harness side and the ACM C240d-4, circuit SME23 (VT/RD), harness side and ground; and between the subwoofer amplifier C466a-1, circuit
SME23 (VT/RD), harness side and ground.

- Is a fluctuating AC voltage present?

Yes
INSTALL a new subwoofer amplifier. REFER to Subwoofer Amplifier Subwoofer Amplifier. CLEAR any DTCs present. TEST the system for normal operation.

No
GO to D9.

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D9 CHECK THE AUDIO CIRCUITS TO THE SUBWOOFER AMPLIFIER FOR A SHORT TO VOLTAGE

- Ignition OFF.
- Measure the voltage between the subwoofer amplifier C466a-7, circuit VME22 (VT/GN), harness side ground; and between the subwoofer amplifier C466a-8, circuit RME22 (GN/WH), harness side and ground.

- Is any voltage present?

Yes
REPAIR the circuit in question. CLEAR any DTCs present. TEST the system for normal operation.

No
GO to D10.

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D10 CHECK THE AUDIO CIRCUITS TO THE SUBWOOFER AMPLIFIER FOR AN OPEN OR SHORT TO GROUND

- Measure the resistance between the subwoofer amplifier, harness side and the ACM, harness side; and between the subwoofer amplifier, harness side and ground as follows:

- Is the resistance less than 5 ohms between the subwoofer amplifier and the ACM, and greater than 10,000 ohms between the subwoofer amplifier and ground?

Yes
GO to D28.

No
REPAIR the circuit in question. CLEAR any DTCs present. TEST the system for normal operation.

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D11 CHECK THE AUDIO SIGNAL TO THE SUSPECT SUBWOOFER SPEAKER

- Ignition OFF.
- Disconnect: Suspect Subwoofer Speaker .
- Ignition ON.
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the LH subwoofer speaker C3120-1, circuit VME01 (GN/VT), harness side and the LH subwoofer speaker C3120-2, circuit RME01 (GY), harness side; or between the RH subwoofer speaker C3121-1, circuit VME02 (VT), harness side and the RH subwoofer speaker C3121-2, circuit RME02 (YE), harness side.

- Is a fluctuating AC voltage present?

Yes
INSTALL a new subwoofer speaker for the suspect speaker. REFER to Speaker - Subwoofer Speaker - Subwoofer. TEST the system for normal operation.

No
GO to D12.

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D12 CHECK THE AUDIO CIRCUITS TO THE SUSPECT SUBWOOFER SPEAKER FOR A SHORT TO VOLTAGE

- Ignition OFF.
- Disconnect: Subwoofer Amplifier C466b .
- Ignition ON.
- Measure the voltage between the suspect subwoofer 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 D13.

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D13 CHECK THE AUDIO CIRCUITS TO THE SUSPECT SUBWOOFER SPEAKER FOR AN OPEN OR SHORT TO GROUND

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

- Is the resistance less than 5 ohms between the suspect subwoofer speaker and the subwoofer amplifier, and greater than 10,000 ohms between the suspect subwoofer speaker and ground?

Yes
INSTALL a new subwoofer amplifier. REFER to Subwoofer Amplifier Subwoofer Amplifier. TEST the system for normal operation.

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

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D14 CHECK FOR AN AUDIO SIGNAL TO THE SUSPECT TWEETER SPEAKER

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

- Is a fluctuating AC voltage present?

Yes
INSTALL a new speaker for the suspect tweeter speaker. REFER to Speaker - Door Speaker - Door. CLEAR any DTCs present. TEST the system for normal operation.

No
GO to D15.

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D15 CHECK THE CIRCUITS TO THE SUSPECT TWEETER SPEAKER FOR A SHORT TO VOLTAGE

- Ignition OFF.
- Disconnect: LF Door Speaker C592b (LH Speaker Concern) or RF Door Speaker C692b (RH Speaker Concern) .
- Ignition ON.
- Measure the voltage between the suspect tweeter speaker, harness side and ground as follows:

- Is any voltage present?

Yes
REPAIR the circuit in question. CLEAR any DTCs present. TEST the system for normal operation.

No
GO to D16.

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D16 CHECK THE CIRCUITS TO THE SUSPECT TWEETER SPEAKER FOR AN OPEN OR SHORT TO GROUND

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

- Is the resistance less than 5 ohms between the suspect tweeter speaker and the door speaker, and greater than 10,000 ohms between the suspect tweeter speaker and ground?

Yes
INSTALL a new door speaker. REFER to Speaker - Door Speaker - Door. CLEAR any DTCs present. TEST the system for normal operation.

No
REPAIR the circuit in question. CLEAR any DTCs present. TEST the system for normal operation.

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D17 CHECK THE AUDIO SIGNALS TO THE SUSPECT SPEAKER

- Ignition OFF.
- Disconnect: Suspect Speaker .
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the suspect speaker pins, harness side as follows:

- Is a fluctuating AC voltage present?

Yes
INSTALL a new speaker for the suspect speaker. REFER to Speaker - Door Speaker - Door. CLEAR any DTCs present. TEST the system for normal operation.

No
GO to D18.

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D18 CHECK THE AUDIO AMPLIFIER VOLTAGE

- Ignition OFF.
- Disconnect: Audio Amplifier C4208a .
- Measure the voltage between the audio amplifier C4208a-12, circuit SBB20 (GN/RD), harness side and ground; and between the audio amplifier C4208a-24, circuit SBB21 (GY/RD), harness side and ground.

- Are the voltages greater than 10 volts?

Yes
GO to D19.

No
VERIFY the Smart Junction Box (SJB) fuses 20 (20A) and 21 (20) are 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 Diagrams By Number.

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D19 CHECK THE AUDIO AMPLIFIER GROUND CIRCUITS FOR CONTINUITY

- Ignition OFF.
- Disconnect: Negative Battery Cable .
- Measure the resistance between the audio amplifier C4208a-21, circuit GD148 (BK/YE), harness side and ground; and between the audio amplifier C4208a-22, circuit GD148 (BK/YE), harness side and ground.

- Are the resistances less than 5 ohms?

Yes
GO to D20.

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

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D20 CHECK THE AUDIO AMPLIFIER ENABLE CIRCUIT FOR CORRECT VOLTAGE

- Ignition OFF.
- Connect: Audio Amplifier C4208a .
- Disconnect: Audio Amplifier C4208b .
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the voltage between the audio amplifier C4208b-11, circuit SME56 (BN), harness side and ground.

- Is the voltage between 3.8 and 6.7 volts?

Yes
GO to D23.

No
GO to D21.

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D21 CHECK THE AUDIO AMPLIFIER ENABLE CIRCUIT FOR A SHORT VOLTAGE

- Ignition OFF.
- Connect: ACM C240d .
- Ignition ON.
- Measure the voltage between the audio amplifier C4208b-11, circuit SME56 (BN), harness side and ground.

- Is any voltage present?

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

No
GO to D22.

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D22 CHECK THE AUDIO AMPLIFIER ENABLE CIRCUIT FOR AN OPEN OR SHORT TO GROUND

- Ignition OFF.
- Measure the resistance between the audio amplifier C4208b-11, circuit SME56 (BN), harness side and the ACM C240d-8, circuit SME56 (BN), harness side; and between the audio amplifier C4208b-11, circuit SME56 (BN), harness side and ground.

- Is the resistance less than 5 ohms between the audio amplifier and the ACM, and greater than 10,000 ohms between the audio amplifier and ground?

Yes
GO to D28.

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

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D23 CHECK THE AUDIO SIGNALS TO THE AUDIO AMPLIFIER

- Connect: Audio Amplifier C4208a .
- Disconnect: Audio Amplifier C4208b .
- Ignition ON.
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the audio amplifier pins, harness side as follows:

- Is any voltage present?

Yes
GO to D24.

No
GO to D26.

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D24 CHECK THE SPEAKER CIRCUITS FOR A SHORT TO VOLTAGE

- Ignition OFF.
- Connect: Audio Amplifier C4208b .
- Disconnect: Audio Amplifier C4208a .
- 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 D25.

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D25 CHECK THE SPEAKER CIRCUITS FOR AN OPEN OR SHORT TO GROUND

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

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

Yes
INSTALL a new audio amplifier. REFER to Audio Amplifier Audio Amplifier. TEST the system for normal operation.

No
REPAIR the circuit in question. CLEAR any DTCs present. TEST the system for normal operation.

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D26 CHECK THE AUDIO CIRCUITS TO THE AUDIO AMPLIFIER FOR A SHORT TO VOLTAGE

- Ignition OFF.
- Connect: ACM C240a (Except Instrument Panel Speaker Concern) or C240d (Instrument Panel Speaker Concern) .
- Ignition ON.
- Measure the voltage between the audio amplifier, 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 D27.

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D27 CHECK THE AUDIO CIRCUITS TO THE AUDIO AMPLIFIER FOR AN OPEN OR SHORT TO GROUND

- Ignition OFF.
- Measure the resistance between the ACM, harness side and the audio amplifier, harness side; and between the ACM, harness side and ground as follows:

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

Yes
GO to D28.

No
REPAIR the circuit in question. CLEAR any DTCs present. TEST the system for normal operation.

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D28 CHECK FOR CORRECT ACM OPERATION

- Disconnect all the ACM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the ACM connectors and make sure they seat correctly.
- Operate the system and determine if the concern is still present.
- Is the concern still present?

Yes
INSTALL a new ACM. REFER to Audio Control Module (ACM) - Fusion, Milan Audio Control Module (ACM) or Audio Control Module (ACM) - MKZ Audio Control Module (ACM). TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR any DTCs present.

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