Pinpoint Test C: The Subwoofer Is Inoperative/Does Not Operate Correctly - Audiophile
Information and Entertainment System
Pinpoint Tests
Pinpoint Test C: The Subwoofer is Inoperative/Does Not Operate Correctly - Audiophile
Refer to Wiring Diagram Set 130, Audio System/Navigation for schematic and connector information. Diagrams By Number
Normal Operation
The subwoofer speaker is powered by a separate subwoofer amplifier. For wagon, the subwoofer speaker is integral to the subwoofer enclosure. For sedan, there are 2 subwoofer speakers connected to the subwoofer amplifier through circuits VME01 (GN/VT), RME01 (GY), VME02 (VT), and RME02 (YE). The subwoofer receives audio signals from the Audio Control Module (ACM) through circuits VME22 (VT/GN) and RME22 (GN/WH). The subwoofer amplifier receives voltage (at all times) through circuit SBP38 (BN/RD), and ground through circuit GD148 (BK/YE).
To enable the subwoofer amplifier, the ACM sends voltage through the enable/clip circuit SME23 (VT/RD). The circuit acts as both an output (to enable the amplifier) and an input (to detect an amplifier overload condition). A variable resistor in the subwoofer amplifier modifies the voltage signal from the ACM. In the event of an overload, the ACM clips the audio output signal to the amplifier (heard as distortion), in order to prevent damage to the amplifier and speakers.
The clip/enable status is based on the following voltages, as detected by the ACM:
- Less than 0.4 volts: amplifier disabled
- Between 3.8 and 6.7 volts: amplifier enabled
- Greater than 8.5 volts: amplifier clipped
An open in circuit SME23 (VT/RD) causes the subwoofer to produce no sound, because the enable signal will not reach the subwoofer amplifier. A short to ground or short to voltage can cause severe distortion to be heard from the subwoofer.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Subwoofer amplifier
- Subwoofer speaker
- ACM
PINPOINT TEST C: THE SUBWOOFER IS INOPERATIVE/DOES NOT OPERATE CORRECTLY - 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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C1 DETERMINE THE VEHICLE TYPE
- Determine the vehicle type.
- Is the vehicle a wagon?
Yes
GO to C3.
No
GO to C2.
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C2 DETERMINE THE INOPERATIVE SUBWOOFER
- Operate the audio system in radio tuner (AM/FM) mode and observe the subwoofer operation.
- Are both subwoofer speakers inoperative?
Yes
GO to C3.
No
GO to C11.
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C3 CHECK CIRCUIT SBP38 (BN/RD) FOR VOLTAGE
- Ignition OFF.
- Disconnect: Subwoofer Amplifier C3041 or C466a.
- Measure the voltage between the subwoofer amplifier C3041-5 or C466a-5, circuit SBP38 (BN/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to C4.
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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C4 CHECK CIRCUIT GD148 (BK/YE) FOR AN OPEN
- Disconnect: Negative Battery Cable.
- Measure the resistance between the subwoofer amplifier C3041-2 or C466a-2, circuit GD148 (BK/YE), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to C5.
No
REPAIR the circuit. TEST the system for normal operation.
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C5 CHECK CIRCUIT SME23 (VT/RD) FOR VOLTAGE
- Connect: Negative Battery Cable.
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the voltage between the subwoofer amplifier C3041-1 or C466a-1, circuit SME23 (VT/RD), harness side and ground.
- Is the voltage between 3.8 and 6.7 volts?
Yes
GO to C8.
No
GO to C6.
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C6 CHECK CIRCUIT SME23 (VT/RD) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM C240b.
- Measure the voltage between the subwoofer amplifier C3041-1 or 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 C7.
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C7 CHECK CIRCUIT SME23 (VT/RD) FOR AN OPEN OR SHORT TO GROUND
- Measure the resistance between the subwoofer amplifier C3041-1 or C466a-1, circuit SME23 (VT/RD), harness side and the ACM C240b-4, circuit SME23 (VT/RD), harness side; and between the subwoofer amplifier C3041-1 or 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 C14.
No
REPAIR the circuit. TEST the system for normal operation.
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C8 CHECK THE AUDIO SIGNAL TO THE SUBWOOFER AMPLIFIER
- Ignition OFF.
- Connect: ACM C240b.
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the subwoofer amplifier C3041-7 or C466a-7, circuit VME22 (VT/GN), harness side and the subwoofer amplifier C3041-8 or C466a-8, circuit RME22 (GN/WH), harness side.
- Is a fluctuating AC voltage present?
Yes
INSTALL a new subwoofer amplifier. REFER to Subwoofer Amplifier Service and Repair. TEST the system for normal operation.
No
GO to C9.
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C9 CHECK THE AUDIO CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM C240b.
- Ignition ON.
- Measure the voltage between the subwoofer amplifier C3041-7 or C466a-7, circuit VME22 (VT/GN), harness side and ground; and between the subwoofer amplifier C3041-8 or C466a-8, circuit RME22 (GN/WH), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit in question. TEST the system for normal operation.
No
GO to C10.
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C10 CHECK THE AUDIO CIRCUITS FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- 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 C14.
No
REPAIR the circuit in question. TEST the system for normal operation.
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C11 CHECK THE AUDIO CIRCUITS TO THE SUSPECT SUBWOOFER SPEAKER FOR VOLTAGE
- Ignition OFF.
- Disconnect: Suspect Subwoofer Speaker.
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the LH subwoofer speaker C3120-1, circuit VME02 (VT), harness side and the LH subwoofer speaker C3120-2, circuit RME02 (YE), harness side; or between the RH subwoofer speaker C3121-1, circuit VME01 (GN/VT), harness side and the RH subwoofer speaker C3121-2, circuit RME01 (GY), harness side.
- Is a fluctuating AC voltage present?
Yes
INSTALL a new subwoofer speaker. REFER to Subwoofer Speaker Subwoofer Speaker. TEST the system for normal operation.
No
GO to C12.
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C12 CHECK THE AUDIO CIRCUITS TO THE SUSPECT SUBWOOFER SPEAKER FOR A SHORT TO VOLTAGE
- Disconnect: Subwoofer Amplifier C466b.
- Ignition ON.
- Measure the voltage between the subwoofer 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 C13.
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C13 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 Service and Repair. TEST the system for normal operation.
No
REPAIR the circuit in question. TEST the system for normal operation.
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C14 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) 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.
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