Pinpoint Test D: The Subwoofer Is Inoperative/Does Not Operate Correctly
Information and Entertainment System
Pinpoint Tests
Pinpoint Test D: 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 then 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 amplifier and subwoofer speaker are integral to the enclosure and cannot be serviced separately.
- DTC B1A05:01 (Speaker #5: General Electrical Failure) - sets on-demand when a failure is detected on the audio signal circuitry to the subwoofer. This DTC applies to vehicles with navigation only.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Subwoofer
- ACM
PINPOINT TEST D: 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.
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D1 CHECK THE SUBWOOFER VOLTAGE SUPPLY
- Ignition OFF.
- Disconnect: Subwoofer C466 (Explorer, Mountaineer) or C3041 (Explorer Sport Trac).
- Measure the voltage between the subwoofer C466-6 (Explorer, Mountaineer) or C3041-6 (Explorer Sport Trac), circuit SBB22 (BN/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to D2.
No
VERIFY the Battery Junction Box (BJB) fuse 22 (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. Diagrams By Number
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D2 CHECK THE SUBWOOFER GROUND CIRCUIT FOR CONTINUITY
- Measure the resistance between the subwoofer C466-2 (Explorer, Mountaineer) or C3041-2 (Explorer Sport Trac), circuit GD114 (BK/BU), 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 SUBWOOFER ENABLE CIRCUIT FOR CORRECT VOLTAGE
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the voltage between the subwoofer C466-1 (Explorer, Mountaineer) or C3041-1 (Explorer Sport Trac), circuit SME23 (VT/RD), harness side and ground.
- Is the voltage between 3.8 and 6.7 volts?
Yes
GO to D6.
No
GO to D4.
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D4 CHECK THE SUBWOOFER ENABLE CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM C290c.
- Disconnect: Subwoofer C466 (Explorer, Mountaineer) or C3041 (Explorer Sport Trac).
- Ignition ON.
- Measure the voltage between the subwoofer C466-1 (Explorer, Mountaineer) or C3041-1 (Explorer Sport Trac), 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 CIRCUIT SME23 (VT/RD) FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the subwoofer C466-1 (Explorer, Mountaineer) or C3041-1 (Explorer Sport Trac), circuit SME23 (VT/RD), harness side and the ACM C290c-4, circuit SME23 (VT/RD), harness side; and between the subwoofer C466-1 (Explorer, Mountaineer) or C3041-1 (Explorer Sport Trac), 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 D9.
No
REPAIR the circuit. TEST the system for normal operation.
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D6 CHECK THE AUDIO SIGNAL TO THE SUBWOOFER
- Operate the audio system in radio tuner (AM/FM) mode.
- Measure the AC voltage between the subwoofer C466-7 (Explorer, Mountaineer) or C3041-7 (Explorer Sport Trac), circuit VME22 (VT/GN), harness side and the subwoofer C466-8 (Explorer, Mountaineer) or C3041-8 (Explorer Sport Trac), circuit RME22 (GN/WH), harness side.
- Is a fluctuating AC voltage present?
Yes
INSTALL a new subwoofer. REFER to Subwoofer Speaker - Explorer, Mountaineer Subwoofer Speaker or Subwoofer Speaker - Explorer Sport Trac Subwoofer Speaker. TEST the system for normal operation.
No
GO to D7.
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D7 CHECK THE AUDIO CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ACM C290c.
- Ignition ON.
- Measure the voltage between the subwoofer C466-7 (Explorer, Mountaineer) or C3041-7 (Explorer Sport Trac), circuit VME22 (VT/GN), harness side and ground; and between the subwoofer C466-8 (Explorer, Mountaineer) or C3041-8 (Explorer Sport Trac), 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 D8.
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D8 CHECK THE AUDIO CIRCUITS 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 D9.
No
REPAIR the circuit in question. TEST the system for normal operation.
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D9 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.
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