Pinpoint Test C: The Subwoofer is Inoperative/Does Not Operate Correctly
Information and Entertainment System
Pinpoint Tests
Pinpoint Test C: The Subwoofer is Inoperative/Does Not Operate Correctly
Refer to Wiring Diagram Set 130, Audio System/Navigation for schematic and connector information. Diagrams By Number
Normal Operation
To enable the subwoofer amplifier, 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 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 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: amplifier enabled
- Greater than 8.5 volts: amplifier clipped
An open in the enable/clip circuit causes the subwoofer to produce no sound, because the enable signal does not reach the subwoofer amplifier. A short to ground or short to voltage can cause severe distortion to be heard in the subwoofer.
The subwoofer and subwoofer amplifier are integral to the enclosure and cannot be repaired individually.
- DTC B1A05:01 (Speaker #5: General Electrical Failure) - sets when an open, a short to ground or a short to voltage is detected in the audio output circuits to the subwoofer.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Subwoofer
- ACM
PINPOINT TEST C: THE SUBWOOFER IS INOPERATIVE/DOES NOT OPERATE CORRECTLY
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 CHECK THE SUBWOOFER VOLTAGE
- Ignition OFF.
- Disconnect: Subwoofer C3020 .
- Measure the voltage between the subwoofer C3020-5, circuit SBP38 (BN/RD), harness side and ground; and between the subwoofer C3020-6, circuit SBP38 (BN/RD), harness side and ground.
- Are the voltages greater than 10 volts?
Yes
GO to C2.
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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C2 CHECK THE SUBWOOFER GROUND FOR CONTINUITY
- Disconnect: Negative Battery Cable .
- Measure the resistance between the subwoofer C3020-2, circuit GD143 (BK/VT), harness side and ground; and between the subwoofer C3020-3, circuit GD143 (BK/VT), harness side and ground.
- Are the resistances less than 5 ohms?
Yes
GO to C3.
No
REPAIR the circuit. CLEAR any DTCs present. TEST the system for normal operation.
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C3 CHECK THE SUBWOOFER AMPLIFIER ENABLE CIRCUIT VOLTAGE
- Connect: Negative Battery Cable .
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the voltage between the subwoofer C3020-1, circuit SME23 (VT/RD), harness side and ground.
- Is the voltage between 3.8 and 6.7 volts?
Yes
GO to C6.
No
GO to C4.
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C4 CHECK THE SUBWOOFER ENABLE CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM C240d .
- Ignition ON.
- Measure the voltage between the subwoofer C3020-1, circuit SME23 (VT/RD), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. CLEAR any DTCs present. TEST the system for normal operation.
No
GO to C5.
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C5 CHECK THE SUBWOOFER ENABLE CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the subwoofer C3020-1, circuit SME23 (VT/RD), harness side and the ACM C240d-4, circuit SME23 (VT/RD), harness side; and between the subwoofer C3020-1, circuit SME23 (VT/RD), harness side and ground.
- Is the resistance less than 5 ohms between the subwoofer and the ACM and greater than 10,000 ohms between the subwoofer and ground?
Yes
GO to C9.
No
REPAIR the circuit. CLEAR any DTCs present. TEST the system for normal operation.
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C6 CHECK THE AUDIO SIGNAL TO THE SUBWOOFER
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the subwoofer C3020-7, circuit VME22 (VT/GN), harness side and the subwoofer C3020-8, circuit RME22 (GN/WH), harness side.
- Is a fluctuating AC voltage present?
Yes
INSTALL a new subwoofer. REFER to Subwoofer Speaker Subwoofer Speaker. CLEAR any DTCs present. TEST the system for normal operation.
No
GO to C7.
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C7 CHECK THE AUDIO CIRCUITS TO THE SUBWOOFER FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM C240d .
- Ignition ON.
- Measure the voltage between the subwoofer C3020-7, circuit VME22 (VT/GN), harness side and ground; or between the subwoofer C3020-8, 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 C8.
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C8 CHECK THE AUDIO CIRCUITS TO THE SUBWOOFER FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the subwoofer, harness side and the ACM, harness side; and between the subwoofer, harness side and ground as follows:
- Is the resistance less than 5 ohms between the subwoofer and the ACM and greater than 10,000 ohms between the subwoofer and ground?
Yes
GO to C9.
No
REPAIR the circuit in question. CLEAR any DTCs present. TEST the system for normal operation.
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C9 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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