Pinpoint Test C: Poor Quality/Distorted/No Sound From One Or More Speakers (Not All Speakers) - THX(R) Sound
Information and Entertainment System
Pinpoint Tests
Pinpoint Test C: Poor Quality/Distorted/No Sound From One Or More Speakers (Not All Speakers) - THX(R) Sound
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 Digital Signal Processing (DSP) module in the form of an AC voltage. The audio DSP module boosts the audio signals and sends them to the speakers. The audio DSP module provides internal circuit protection for shorts to ground or shorts to voltage by confirming the headphone icon is displayed in the ACM display.
If the vehicle is equipped with the family entertainment system, the rear channel audio signals from the ACM route to the Rear Entertainment Module (RETM), then to the audio DSP module. In dual-play mode, the RETM mutes the rear speaker output. Make sure the audio system is in single-play mode before diagnosing a speaker concern.
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 audio DSP module. In this case, a speaker fault DTC sets, and this pinpoint test should be followed to isolate the damaged circuit.
The ACM sends the audio signals to the audio DSP module in the following banks:
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Speaker
- Speaker enclosure
- Audio DSP module
- RETM (if equipped)
- ACM
PINPOINT TEST C: POOR QUALITY/DISTORTED/NO SOUND FROM ONE OR MORE SPEAKERS (NOT ALL SPEAKERS) - THX(R) 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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C1 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 a rear door tweeter speaker?
Yes
GO to C2.
No
GO to C5.
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C2 CHECK THE AUDIO SIGNAL TO THE SUSPECT REAR DOOR TWEETER SPEAKER
- Ignition OFF.
- Disconnect: Suspect Rear Door Tweeter Speaker.
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the LH rear door tweeter speaker C730-1, circuit VME39 (GN/BN), harness side and the LH rear door tweeter speaker C730-2, circuit RME39 (GY/BN), harness side; or between the RH rear door tweeter speaker C830-1, circuit VME40 (BU/WH), harness side and the RH rear door tweeter speaker C830-2, circuit RME40 (VT/WH), harness side.
- Is a fluctuating AC voltage present?
Yes
INSTALL a new speaker for the suspect rear door tweeter speaker. REFER to Speaker - Door Speaker - Door. TEST the system for normal operation.
No
GO to C3.
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C3 CHECK THE CIRCUITS TO THE REAR DOOR TWEETER FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: LH Rear Door Speaker C712b (LH Rear Door Tweeter Concern) or RH Rear Door Speaker C813b (RH Rear Door Tweeter 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 C4.
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C4 CHECK THE CIRCUITS TO THE REAR DOOR TWEETER FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the door speaker, harness side and the suspect door tweeter speaker, harness side; and between the door speaker, harness side and ground as follows:
- Is the resistance less than 5 ohms between the door speaker and the suspect door tweeter speaker, and greater than 10,000 ohms between the door 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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C5 CHECK FOR AN AUDIO SIGNAL 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 the appropriate removal and installation procedure. TEST the system for normal operation.
No
GO to C6.
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C6 CHECK FOR AN AUDIO SIGNAL AT THE AUDIO DSP MODULE
- Ignition OFF.
- Disconnect: Audio DSP Module C4326a.
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the audio DSP module pins, harness side as follows:
- Is a fluctuating AC voltage present?
Yes
GO to C7.
No
If the vehicle is equipped with the family entertainment system and the concern is with a rear door speaker, D-pillar speaker, or the subwoofer, GO to C9.
Otherwise, GO to C12.
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C7 CHECK THE CIRCUITS TO THE SPEAKERS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Connect: Audio DSP Module C4326a.
- Disconnect: Audio DSP Module C4326b (Except Subwoofer Concern).
- Disconnect: Audio DSP Module C4326c (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 C8.
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C8 CHECK THE SPEAKER CIRCUITS FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the suspect speaker, harness side and the audio DSP module, harness side; and between the suspect speaker, harness side and ground as follows:
- Are the resistances less than 5 ohms between the suspect speaker and the audio DSP module, and greater than 10,000 ohms between the suspect speaker and ground?
Yes
REPAIR the circuit in question. CLEAR any DTCs present. TEST the system for normal operation.
No
GO to C16.
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C9 CHECK THE AUDIO SIGNALS TO THE RETM
- Ignition OFF.
- Disconnect: RETM C2949b.
- Operate the audio system in radio tuner (AM/FM), single-play mode (no headphone icon on the ACM display).
- Measure the AC voltage between the RETM C2949b-8, circuit VME59 (YE/OG), harness side and the RETM C2949b-21, circuit RME59 (WH/GN), harness side.
- Measure the AC voltage between the RETM C2949b-22, circuit VME58 (YE/VT), harness side and the RETM C2949b-9, circuit RME58 (BN/BU), harness side.
- Is a fluctuating AC voltage present?
Yes
GO to C12.
No
GO to C10.
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C10 CHECK THE AUDIO CIRCUITS TO THE RETM FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM C240a.
- Ignition ON.
- Measure the voltage between the RETM, 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 C11.
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C11 CHECK THE AUDIO CIRCUITS TO THE RETM FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the ACM, harness side and the RETM, harness side; and between the ACM, harness side and ground as follows:
- Are the resistances less than 5 ohms between the ACM and the RETM, and greater than 10,000 ohms between the ACM and ground?
Yes
GO to C14.
No
REPAIR the circuit in question. TEST the system for normal operation.
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C12 CHECK THE AUDIO CIRCUITS TO THE AUDIO DSP MODULE FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM C240a (Except Subwoofer Concern).
- Disconnect: ACM C240d (Subwoofer Concern).
- Disconnect: Audio DSP Module C4326a.
- Ignition ON.
- Measure the voltage between the audio DSP module pins, 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 C13.
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C13 CHECK THE AUDIO CIRCUITS TO THE AUDIO DSP MODULE FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the audio DSP module, harness side and the ACM (vehicles without family entertainment system) or RETM (vehicles with family entertainment system), harness side; and between the audio DSP module, harness side and ground as follows:
- Are the resistances less than 5 ohms between the audio DSP module and the ACM (or RETM), and greater than 10,000 ohms between the audio DSP module and ground?
Yes
If the vehicle is equipped with family entertainment system, GO to C15.
Otherwise, GO to C14.
No
REPAIR the circuit in question. CLEAR any DTCs present. TEST the system for normal operation.
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C14 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 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) 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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C15 CHECK FOR CORRECT RETM OPERATION
- Ignition OFF.
- Connect: All Disconnected Connectors.
- Disconnect all the RETM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the RETM 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 RETM. REFER to Rear Entertainment Module (RETM) Rear Entertainment Module (RETM). 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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C16 CHECK FOR CORRECT AUDIO DSP MODULE OPERATION
- Ignition OFF.
- Connect: All Disconnected Connectors.
- Disconnect all the audio DSP module connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the audio DSP module 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 audio DSP module. REFER to Audio Digital Signal Processing (DSP) Module Audio Digital Signal Processing (DSP) Module. 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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