Pinpoint Test D: The Subwoofer Is Inoperative

WARNING: This page is about a different car, the 2005 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.

D1 CHECK THE SUBWOOFER OPERATION
- Carry out the speaker walk-around test.
- Does the subwoofer operate correctly?
- Yes : The system is operating correctly.
- No : GO to D2.
D2 CHECK CIRCUIT 173 (DG/VT) FOR VOLTAGE
- Key in OFF position.
- Disconnect: Subwoofer Amplifier C3020.
- Key in ON position.
- Turn the audio unit on.
- Measure the voltage between the subwoofer amplifier C3020-1, circuit 173 (DG/VT), harness side and ground.
  
  Fig 1: Measuring Voltage Between Subwoofer Amplifier C3020-1, Circuit 173 (DG/VT), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to D3.
- No : GO to D7.
D3 CHECK CIRCUIT 828 (VT/LB) FOR VOLTAGE
- Key in OFF position.
- Measure the voltage between the subwoofer amplifier C3020-5, circuit 828 (VT/LB), harness side and ground; and between the subwoofer amplifier C3020-6, circuit 828 (VT/LB), harness side and ground.
  
  Fig 2: Checking Circuit 828 (VT/LB) For Voltage
  Courtesy of FORD MOTOR CO.
- Are the voltages greater than 10 volts?
- Yes : GO to D4.
- No : REPAIR the circuit in question. TEST the system for normal operation.
D4 CHECK CIRCUIT 1204 (BK/OG) FOR AN OPEN
- Measure the resistance between the subwoofer amplifier C3020-2, circuit 1204 (BK/OG), harness side and ground; and between the subwoofer amplifier C3020-3, circuit 1204 (BK/OG), harness side and ground.
  
  Fig 3: Checking Circuit 1204 (BK/OG) For An Open
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
- Yes : GO to D5.
- No : REPAIR the circuit in question. TEST the system for normal operation.
D5 CHECK THE SIGNAL CIRCUITS FOR AC VOLTAGE
- Key in ON position.
- Turn the audio unit on.
- Measure the AC voltage between the subwoofer amplifier C3020-7, circuit 167 (BN/OG), harness side and the subwoofer amplifier C3020-8, circuit 168 (RD/BK), harness side.
  
  Fig 4: Checking Signal Circuits For AC Voltage
  Courtesy of FORD MOTOR CO.
- Is the voltage approximately 2 volts AC?
- Yes : SUBSTITUTE a known good subwoofer amplifier.
  If the subwoofer still has no sound, INSTALL a new speaker enclosure. REFER to SPEAKERS .
  
  If the subwoofer operates correctly, REMOVE the subwoofer amplifier. REFER to AUDIO UNIT . SEND the subwoofer amplifier to an authorized repair facility. TEST the system for normal operation after the repair.
- No : GO to D6.

D6 CHECK CIRCUITS 167 (BN/OG) AND 168 (RD/BK) FOR AN OPEN AND A SHORT TO GROUND

Key in OFF position.
Disconnect: Audio Unit C290c.

Measure the resistance between the subwoofer amplifier, harness side and the audio unit, harness side; and between the subwoofer amplifier, harness side and ground as follows:

SUBWOOFER AMPLIFIER & AUDIO UNIT CONNECTOR-PIN & CIRCUITS

Subwoofer Amplifier Connector-Pin	Audio Unit Connector-Pin	Circuit
C3020-7	C290c-l	167 (BN/OG)
C3020-8	C290c-2	168 (RD/BK)

Fig 5: Checking Circuits 167 (BN/OG) And 168 (RD/BK) For An Open And Short To Ground

Courtesy of FORD MOTOR CO.

Is the resistance less than 5 ohms between the subwoofer amplifier and the audio unit, and greater than 10,000 ohms between the subwoofer amplifier and ground?

Yes : SEND the audio unit to an authorized repair facility. TEST the system for normal operation after the repair.
No : REPAIR the circuit in question. TEST the system for normal operation.

D7 CHECK CIRCUIT 173 (DG/VT) FOR AN OPEN OR A SHORT TO GROUND
- Key in OFF position.
- Disconnect: Audio Unit C290c.
- Measure the resistance between the subwoofer amplifier C3020-1, circuit 173 (DG/VT), harness side and the audio unit C290c-4, circuit 173 (DG/VT), harness side; and between the subwoofer amplifier C3020-1, circuit 173 (DG/VT), harness side and ground.
  
  Fig 6: Checking Circuit 173 (DG/VT) For An Open Or A Short To Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms between the subwoofer amplifier and the audio unit, and greater than 10,000 ohms between the subwoofer amplifier and ground?
- Yes : SEND the audio unit to an authorized repair facility. TEST the system for normal operation after the repair
- No : REPAIR the circuit. TEST the system for normal operation.