Pinpoint Test H: The Subwoofer Is Inoperative

WARNING: This page is about a different car, the 2006 Mercury Montego, 2006 Ford Freestyle, and 2006 Ford Five Hundred. However, it is still accessible from the selected car via links, so may be relevant.

H1 CHECK THE SUBWOOFER SPEAKERS
- Perform the speaker walk-around test.
- Are all subwoofer speakers inoperative?
Yes: GO to H2.

No: GO to H11.
H2 CHECK CIRCUIT 1678 (WH/VT) FOR VOLTAGE
- Key in OFF position.
- Disconnect: Subwoofer Amplifier C3041 or C466a.
- Measure the voltage between the subwoofer amplifier C3041-5 or C466a-5, circuit 1678 (WH/VT), harness side and ground.
  
  Fig 1: Measuring Voltage Between Subwoofer Amplifier C3041-5 Or C466a-5, Circuit 1678 (WH/VT), Harness Side & Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes: GO to H3.

No: VERIFY the smart junction box (SJB) fuse 6 (20A) is OK. If OK, REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
H3 CHECK CIRCUIT 1204 (BK/OG) FOR AN OPEN
- Measure the resistance between the subwoofer amplifier C3041-2 or C466a-2, circuit 1204 (BK/OG), harness side and ground.
  
  Fig 2: Measuring Resistance Between Subwoofer Amplifier C3041-2 Or C466a-2, Circuit 1204 (BK/OG), Harness Side & Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes: GO to H4.

No: REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
H4 CHECK CIRCUIT 174 (GY/BK) FOR VOLTAGE
- Key in ON position.
- Operate the audio unit in radio tuner mode.
- Measure the voltage between the subwoofer amplifier C3041-1 or C466a-1, circuit 174 (GY/BK), harness side and ground.
  
  Fig 3: Measuring Voltage Between Connector Terminal And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage approximately 4.1 volts?
Yes: GO to H5.

No: GO to H9.
H5 CHECK FOR AN OUTPUT SIGNAL FROM THE AUDIO UNIT
- With the audio unit still in radio tuner mode, measure the voltage between the subwoofer amplifier C3041-7 or C466a-7, circuit 176 (PK/LG), harness side and the subwoofer amplifier C3041-8 or C466a-8, circuit 179 (OG/RD), harness side.
  
  Fig 4: Checking For Output Signal From Audio Unit
  Courtesy of FORD MOTOR CO.
- Is there a fluctuating AC voltage?
Yes: REMOVE the new subwoofer amplifier. REFER to SUBWOOFER AMPLIFIER . SEND it to an authorized audio system repair facility. CLEAR the DTCs. REPEAT the self-test.

No: GO to H6.
H6 CHECK CIRCUITS 176 (PK/LG) AND 179 (OG/RD) FOR AN OPEN
- Key in OFF position.
- Disconnect: Audio Unit C240b.
- Measure the resistances between the subwoofer amplifier C3041-7 or C466a-7, circuit 176 (PK/LG), harness side and the audio unit C240b-1, circuit 176 (PK/LG), harness side; and between the subwoofer amplifier C3041-8 or C466a-8, circuit 179 (OG/RD), harness side and the audio unit C240b-2, circuit 179 (OG/RD), harness side.
  
  Fig 5: Checking Circuits 176 (PK/LG) & 179 (OG/RD) For Open
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
Yes: GO to H7.

No: REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
H7 CHECK CIRCUITS 176 (PK/LG) AND 179 (OG/RD) FOR A SHORT TO GROUND
- Measure the resistance between the subwoofer amplifier C3041-7 or C466a-7, circuit 176 (PK/LG), harness side and ground; and between the subwoofer amplifier C3041-8, circuit 179 (OG/RD), harness side and ground.
  
  Fig 6: Checking Circuits 176 (PK/LG) & 179 (OG/RD) For Short To Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes: GO to H8.

No: REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
H8 CHECK CIRCUITS 176 (PK/LG) AND 179 (OG/RD) FOR A SHORT TO VOLTAGE
- Measure the voltage between the subwoofer amplifier 03041-7 or 466a-7, circuit 176 (PK/LG), harness side and ground; and between the subwoofer amplifier C3041-8, circuit 179 (OG/RD), harness side and ground.
  
  Fig 7: Checking Circuits 176 (PK/LG) & 179 (OG/RD) For Short To Voltage
  Courtesy of FORD MOTOR CO.
- Is any voltage present?
Yes: REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.

No: GO to H9.
H9 CHECK CIRCUIT 174 (GY/BK) FOR AN OPEN
- Measure the resistance between the subwoofer amplifier C3041-1 or C466a-1, circuit 174 (GY/BK), harness side and the audio unit C240b-4, circuit 174 (GY/BK), harness side
  
  Fig 8: Measuring Resistance Between Subwoofer Amplifier C3041-1 Or C466a-1, Circuit 174 (GY/BK), Harness Side & Audio Unit C240b-4, Circuit 174 (GY/BK), Harness Side
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes: GO to H10.

No: REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
H10 CHECK CIRCUIT 174 (GY/BK) FOR A SHORT TO GROUND
- Measure the resistance between the subwoofer amplifier C3041-1 or C466a-1, circuit 174 (GY/BK), harness side and ground.
  
  Fig 9: Measuring Resistance Between Subwoofer Amplifier C3041-1 Or C466a-1, Circuit 174 (GY/BK), Harness Side & Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes: GO to H14.

No: REPAIR the circuit. TEST the system for normal operation.

H11 CHECK THE SUBWOOFER OUTPUT SIGNAL

Key in OFF position.
Disconnect: Suspect Subwoofer Speaker.
Key in ON position.
Operate the audio unit in radio tuner mode.

Measure the AC voltage between the suspect subwoofer speaker pins, harness side as follows:

SUBWOOFER OUTPUT SIGNAL SPECIFICATION

Speaker Connector-Pin, Circuit	Speaker Connector-Pin, Circuit
C3120-1 825 (TN/LG)	C3120-2 824 (WH/VT)
C3121-1 827 (TN/WH)	C3121-2 826 (DB/OG)

Is a fluctuating AC voltage present?

Yes: INSTALL a new subwoofer speaker. REFER to SUBWOOFER SPEAKER . TEST the system for normal operation.

No: GO to H12.

H12 CHECK THE SUBWOOFER SPEAKER CIRCUITS FOR AN OPEN OR SHORT TO GROUND

Key in OFF position.
Disconnect: Subwoofer Amplifier C3041.

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:

SUBWOOFER SPEAKER CIRCUITS SPECIFICATION

Speaker Connector-Pin	Subwoofer Amplifier Connector-Pin	Circuit
C3120-1	C466b-3	825 (TN/LG)
C3120-2	C466b-4	824 (WH/VT)
C3121-1	C466b-1	827 (TN/WH)
C3121-2	C466b-2	826 (DB/OG)

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: GO to H13.

No: REPAIR the circuit. TEST the system for normal operation.

H13 CHECK THE SUBWOOFER SPEAKER CIRCUITS FOR A SHORT TO VOLTAGE

Key in ON position.

Measure the voltage between the subwoofer amplifier, harness side and ground as follows:

SUBWOOFER SPEAKER CIRCUITS SPECIFICATION

Subwoofer Amplifier Connector-Pin	Circuit
C466b-3	825 (TN/LG)
C466b-4	824 (WH/VT)
C466b-1	827 (TN/WH)
C466b-2	826 (DB/OG)

Is any voltage present?

Yes: REPAIR the circuit. TEST the system for normal operation.

No: REMOVE the subwoofer amplifier. REFER to SUBWOOFER AMPLIFIER . SEND it to an authorized audio system repair facility. TEST the system for normal operation.

H14 CHECK FOR CORRECT AUDIO UNIT OPERATION
- Disconnect the audio unit connectors.
- Check for:
  - corrosion
  - pushed-out pins
- Connect the audio unit connectors and make sure they seat correctly.
- Operate the system and determine if the concern is still present.
- Is the concern still present?
Yes: REMOVE the audio unit. REFER to AUDIO UNIT . SEND it to an authorized audio system repair facility. TEST the system for normal operation after the repair.

No: The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.