Pinpoint Test D: Poor Quality/Distorted/No Sound From The Door Subwoofer(s)
Information and Entertainment System
Pinpoint Tests
Pinpoint Test D: Poor Quality/Distorted/No Sound From The Door Subwoofer(s)
Refer to Wiring Diagram Set 130, Audio System/Navigation for schematic and connector information. Diagrams By Number
Normal Operation
To enable the amplifiers, the Audio Control Module (ACM) sends voltage through the enable/clip circuit. The circuit acts 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.
- DTC B1A05:01 (Speaker #5: General Electrical Failure) - can set when any fault is detected in the subwoofer speaker circuits. This DTC can be either continuous or on-demand.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Door subwoofer speaker
- Door subwoofer amplifier
- ACM
PINPOINT TEST D: POOR QUALITY/DISTORTED/NO SOUND FROM THE DOOR SUBWOOFER(S)
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, Mounting and Cables Service and Repair.
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D1 CHECK THE DOOR SUBWOOFER AMPLIFIER CIRCUIT FOR VOLTAGE
- Ignition OFF.
- Disconnect: Left Door Subwoofer Amplifier C2993a (Left Subwoofer Concern) or Right Door Subwoofer Amplifier C2994a (Right Subwoofer Concern).
- Measure the voltage between the left door subwoofer amplifier C2993a-5, circuit SBB33 (RD), harness side and ground; or between the right front subwoofer amplifier C2994a-5, circuit SBB33 (RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to D2.
No
VERIFY the SJB fuse 33 (30A) 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. Diagrams By Number
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D2 CHECK THE DOOR SUBWOOFER AMPLIFIER GROUND CIRCUIT FOR AN OPEN
- Disconnect: Negative Battery Cable.
- Measure the resistance between the left door subwoofer amplifier C2993a-2, circuit GD115 (BK/GY), harness side and ground; or between the right door subwoofer amplifier C2994a-2, circuit GD115 (BK/GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to D3.
No
REPAIR the circuit. TEST the system for normal operation.
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D3 CHECK THE DOOR 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 left door subwoofer amplifier C2993a-1, circuit SME23 (VT/RD), harness side and ground; and between the right door subwoofer amplifier C2994a-1, circuit SME23 (VT/RD), harness side and ground.
- Is the voltage between 3.8 and 6.7 volts at both amplifiers?
Yes
GO to D6.
No
If the voltage is incorrect at one amplifier only, REPAIR the circuit in question. TEST the system for normal operation.
If the voltage is incorrect at both amplifiers, GO to D4.
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D4 CHECK THE DOOR SUBWOOFER AMPLIFIER ENABLE CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM C290b.
- Ignition ON.
- Measure the voltage between the left door subwoofer amplifier C2993a-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 D5.
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D5 CHECK THE DOOR SUBWOOFER AMPLIFIER ENABLE CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the left door subwoofer amplifier C2993a-1, circuit SME23 (VT/RD), harness side and the ACM C290b-4, circuit SME23 (VT/RD), harness side; and between the left door subwoofer amplifier C2993a-1, circuit SME23 (VT/RD), harness side and ground.
- Is the resistance less than 5 ohms between the left door subwoofer amplifier and the ACM, and greater than 10,000 ohms between the left door subwoofer amplifier and ground?
Yes
GO to D13.
No
REPAIR the circuit. TEST the system for normal operation.
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D6 CHECK THE AUDIO SIGNALS TO THE DOOR SUBWOOFER AMPLIFIER
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the left door subwoofer amplifier C2993a-7, circuit VME22 (VT/GN), harness side and the left door subwoofer amplifier C2993a-8, circuit RME22 (GN/WH), harness side; and between the right door subwoofer amplifier C2994a-7, circuit VME22 (VT/GN), harness side and the right door subwoofer amplifier C2994a-8, circuit RME22 (GN/WH), harness side.
- Is a fluctuating AC voltage present at both amplifiers?
Yes
GO to D10.
No
If the voltage is incorrect at one amplifier only, GO to D7 .
If the voltage is incorrect at both amplifiers, GO to D8 .
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D7 CHECK THE SPEAKER CIRCUITS FOR AN OPEN
NOTE: Carry out this step only for the inoperative subwoofer.
- Ignition OFF.
- Disconnect: ACM C290b.
- Measure the resistance between the left door subwoofer amplifier C2993a-7, circuit VME22 (VT/GN), harness side and the ACM C290b-1, circuit VME22 (VT/GN), harness side; or between the right door subwoofer amplifier C2994a-7, circuit VME22 (VT/GN), harness side and the ACM C290b-1, circuit VME22 (VT/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
REPAIR circuit RME22 (GN/WH). TEST the system for normal operation.
No
REPAIR circuit VME22 (VT/GN). TEST the system for normal operation.
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D8 CHECK THE SPEAKER CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM C290b.
- Ignition ON.
- Measure the voltage between the left door subwoofer amplifier C2993a-7, circuit VME22 (VT/GN), harness side and ground; and between the left door subwoofer amplifier C2993a-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 D9.
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D9 CHECK THE SPEAKER CIRCUITS FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the suspect subwoofer amplifier, harness side and the ACM, harness side; and between the suspect subwoofer amplifier, harness side and ground as follows:
- Is the resistance less than 5 ohms between the suspect door subwoofer amplifier and the ACM, and greater than 10,000 ohms between the suspect door subwoofer amplifier and ground?
Yes
GO to D13.
No
REPAIR the circuit in question. TEST the system for normal operation.
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D10 CHECK THE AUDIO CIRCUITS TO THE SUSPECT DOOR SUBWOOFER
- Ignition OFF.
- Connect: Left Door Subwoofer Amplifier C2993b and Right Door Subwoofer Amplifier C2994b.
- Disconnect: Left Door Subwoofer C536 (Left Subwoofer Concern) or Right Door Subwoofer C628 (Right Subwoofer Concern).
- Ignition ON.
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the suspect door subwoofer circuits, harness side as follows:
- Is a fluctuating AC voltage present?
Yes
INSTALL a new subwoofer for the suspect subwoofer. REFER to Speaker - Door Speaker - Door. TEST the system for normal operation.
No
GO to D11.
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D11 CHECK THE AUDIO CIRCUITS TO THE SUSPECT DOOR SUBWOOFER FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: Left Door Subwoofer Amplifier C2993b Or Right Door Subwoofer Amplifier C2994b.
- Ignition ON.
- Measure the voltage between the suspect door subwoofer, 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 D12.
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D12 CHECK THE AUDIO CIRCUITS TO THE SUSPECT DOOR SUBWOOFER FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the suspect door subwoofer, harness side and the door amplifier, harness side; and between the suspect door subwoofer, harness side and ground as follows:
- Is the resistance less than 5 ohms between the suspect door subwoofer and the door subwoofer amplifier, and greater than 10,000 ohms between the suspect door subwoofer and ground?
Yes
INSTALL a new door subwoofer amplifier for the suspect amplifier. REFER to Subwoofer Amplifier - Door Subwoofer Amplifier - Door. TEST the system for normal operation.
No
REPAIR the circuit in question. TEST the system for normal operation.
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D13 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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