Pinpoint Test B: Poor Quality/Distorted/No Sound From One Or More Speakers (Not All Speakers) - Audiophile
Information and Entertainment System
Pinpoint Tests
Pinpoint Test B: Poor Quality/Distorted/No Sound From One Or More Speakers (Not All Speakers) - Audiophile
Refer to Wiring Diagram Set 130, 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 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 on the same channel, or even all speakers to lose sound due to the built-in overload protection feature of the ACM. In this case, a speaker fault DTC should set, and this pinpoint test should be followed to isolate the damaged circuit. It is important to note that the ACM may not set a DTC, even when a fault exists in the circuitry to the amplifiers.
The amplifiers are enabled by individual enable/clip circuits. To enable the amplifiers, the ACM sends voltage through the enable/clip circuits. The circuits act as both an output (to enable the amplifier) and an input (to detect an amplifier overload condition). The voltage sent by the ACM passes through a variable resistor in the subwoofer 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 the speakers.
The enable/clip status is based on the following voltages, as detected by the ACM:
- Less then 0.4 volt: amplifier disabled
- Between 3.8 and 6.7 volts: amplifier enabled
- Greater than 8.5 volts: amplifier clipped
B1A01-B1A06:
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Speaker
- Subwoofer speaker
- Audio amplifier
- Subwoofer amplifier
- ACM
PINPOINT TEST B: POOR QUALITY/DISTORTED/NO SOUND FROM ONE OR MORE SPEAKERS (NOT ALL SPEAKERS) - AUDIOPHILE
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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B1 DETERMINE THE INOPERATIVE SPEAKER(S)
- Enter the following diagnostic mode on the scan tool: Speaker Walkaround Test.
- Follow the scan tool on-screen instructions to carry-out the speaker walkaround test.
- Is the concern only with an A-pillar speaker?
Yes
GO to B2.
No
GO to B5.
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B2 CHECK FOR VOLTAGE TO THE SUSPECT A-PILLAR SPEAKER
- Ignition OFF.
- Disconnect: Suspect A-Pillar Speaker.
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the suspect A-pillar speaker pin 1 and pin 2, harness side as follows:
- Is a fluctuating AC voltage present?
Yes
INSTALL a new speaker for the suspect A-pillar speaker. REFER to Speaker - A-Pillar Speaker - A-Pillar. CLEAR any DTCs present. TEST the system for normal operation.
No
GO to B3.
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B3 CHECK THE A-PILLAR SPEAKER CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: LH Front Door Speaker C523 or RH Front Door Speaker C652.
- Ignition ON.
- Measure the voltage between the suspect A-pillar 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 B4.
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B4 CHECK THE A-PILLAR SPEAKER CIRCUITS FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the suspect A-pillar speaker, harness side and the respective door speaker, harness side; and between the suspect A-pillar speaker, harness side and ground as follows:
- Is the resistance less than 5 ohms between the suspect A-pillar speaker and the door speaker, and greater than 10,000 ohms between the suspect A-pillar 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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B5 CHECK FOR VOLTAGE AT THE SUSPECT SPEAKER
NOTE: For this step, both subwoofer speakers must have a fluctuating AC voltage present in order to condemn the subwoofer 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, Speaker - Instrument Panel Speaker - Instrument Panel, or Speaker - Subwoofer Speaker - Subwoofer. CLEAR any DTCs present. TEST the system for normal operation.
No
If the concern is with the subwoofer speaker, GO to B11.
For all other speaker concerns, GO to B6.
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B6 CHECK THE AUDIO AMPLIFIER VOLTAGE
- Ignition OFF.
- Disconnect: Audio Amplifier C4208b.
- Measure the voltage between the audio amplifier C4208b-12, circuit SBP38 (BN/RD), harness side and ground; and between the audio amplifier C4208b-24, circuit SBP38 (BN/RD), harness side and ground.
- Are the voltages greater than 10 volts?
Yes
GO to B7.
No
VERIFY the Smart Junction Box (SJB) fuse 38 (20A) 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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B7 CHECK THE AUDIO AMPLIFIER GROUND
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the audio amplifier C4208b-21, circuit GD149 (BK/GY), harness side and ground; and between the audio amplifier C4208b-22, circuit GD149 (BK/GY), harness side and ground.
- Are the resistances less than 5 ohms?
Yes
GO to B8.
No
REPAIR the circuit in question. TEST the system for normal operation.
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B8 CHECK THE AUDIO AMPLIFIER ENABLE CIRCUIT FOR CORRECT VOLTAGE
- Connect: Audio Amplifier C4208b.
- Connect: Negative Battery Cable.
- Disconnect: Audio Amplifier C4208a.
- Measure the voltage between the audio amplifier C4208a-11, circuit CME31 (BU/GN), harness side and ground.
- Is the voltage between 3.8 and 6.7 volts?
Yes
GO to B16.
No
GO to B9.
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B9 CHECK THE AUDIO AMPLIFIER ENABLE CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: ACM C240d.
- Measure the voltage between the audio amplifier C4208a-11, circuit CME31 (BU/GN), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. TEST the system for normal operation.
No
GO to B10.
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B10 CHECK THE AUDIO AMPLIFIER ENABLE CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Measure the resistance between the audio amplifier C4208a-11, circuit CME31 (BU/GN), harness side and the ACM C240d-8, circuit CME31 (BU/GN); and between the audio amplifier C4208a-11, circuit CME31 (BU/GN), 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 B21.
No
REPAIR the circuit. TEST the system for normal operation.
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B11 CHECK THE SUBWOOFER AMPLIFIER VOLTAGE
- Ignition OFF.
- Disconnect: Subwoofer Amplifier C466a.
- Measure the voltage between the subwoofer amplifier C466a-5, circuit SBP40 (VT/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to B12.
No
VERIFY the SJB fuse 40 (20A) 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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B12 CHECK THE SUBWOOFER AMPLIFIER GROUND
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the subwoofer amplifier C466a-2, circuit GD149 (BK/GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to B13.
No
REPAIR the circuit in question. TEST the system for normal operation.
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B13 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 B16.
No
GO to B14.
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B14 CHECK THE SUBWOOFER AMPLIFIER ENABLE CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM C240d.
- 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 B15.
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B15 CHECK THE SUBWOOFER AMPLIFIER ENABLE CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Measure the resistance between the subwoofer amplifier C466a-1, circuit SME23 (VT/RD), harness side and the ACM C240d-4, circuit SME23 (VT/RD); and between the subwoofer amplifier C466a-1, circuit SME23 (VT/RD), harness side and ground.
- 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 B21.
No
REPAIR the circuit. TEST the system for normal operation.
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B16 CHECK FOR AN AUDIO SIGNAL AT THE AMPLIFIER
- Ignition OFF.
- Connect: Suspect Speaker.
- Connect: ACM C240d.
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the audio amplifier (or subwoofer amplifier) pins, harness side as follows:
- Is a fluctuating AC voltage present?
Yes
GO to B17.
No
GO to B19.
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B17 CHECK THE SPEAKER CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Connect: Audio Amplifier C4208a.
- Connect: Subwoofer Amplifier C466a.
- Disconnect: Audio Amplifier C4208b (Except Subwoofer Concern).
- Disconnect: Subwoofer Amplifier C466b (Subwoofer Concern).
- 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. CLEAR any DTCs present. TEST the system for normal operation.
No
GO to B18.
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B18 CHECK THE SPEAKER CIRCUITS FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the audio amplifier (or subwoofer amplifier), harness side and the suspect speaker, harness side; and between the audio amplifier (or subwoofer amplifier), harness side and ground as follows:
- Are the resistances less than 5 ohms between the audio amplifier (or subwoofer amplifier) and the suspect speaker, and greater than 10,000 ohms between the audio amplifier (or subwoofer amplifier) and ground?
Yes
INSTALL a new audio amplifier (except subwoofer concern) or subwoofer amplifier (subwoofer concern). REFER to Audio Amplifier Audio Amplifier or Subwoofer Amplifier Subwoofer Amplifier. 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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B19 CHECK THE AUDIO CIRCUITS TO THE AMPLIFIER FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM C240a (Except Subwoofer Concern) or C240d (Subwoofer Concern).
- Disconnect: Audio Amplifier C4208a (Except Subwoofer Concern).
- Disconnect: Subwoofer Amplifier C466a (Subwoofer Concern).
- Ignition ON.
- Measure the voltage between the audio amplifier (or subwoofer amplifier), 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 B20.
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B20 CHECK THE AUDIO CIRCUITS TO THE AMPLIFIER FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the audio amplifier (or subwoofer amplifier), harness side and the ACM, harness side; and between the audio amplifier (or subwoofer amplifier), harness side and ground as follows:
- Are the resistances less than 5 ohms between the audio amplifier (or subwoofer amplifier) and the ACM, and greater than 10,000 ohms between the audio amplifier (or subwoofer amplifier) and ground?
Yes
GO to B21.
No
REPAIR the circuit in question. CLEAR any DTCs present. TEST the system for normal operation.
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B21 CHECK FOR CORRECT ACM OPERATION
- Ignition OFF.
- Connect: All Disconnected Connectors.
- Disconnect all the ACM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect 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) 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. TEST the system for normal operation.
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