Pinpoint Test L: The Subwoofer Is Inoperative

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

L1 CHECK CIRCUIT 174 (GY/BK) FOR VOLTAGE
- Key in OFF position.
- Disconnect: Subwoofer Amplifier.
- Key in ON position.
- Turn the audio unit on.
- Measure the voltage between the subwoofer amplifier C466-1, circuit 174 (GY/BK), harness side and ground.
  
  Fig 1: Checking Circuit 174 (GY/BK) For Voltage
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 4.1 volts?
Yes : GO to L2.

No : GO to L6.
L2 CHECK CIRCUIT 720 (RD/YE) FOR VOLTAGE
- Key in OFF position.
- Measure the voltage between the subwoofer amplifier C466-5, circuit 720 (RD/YE), harness side and ground.
  
  Fig 2: Checking Circuit 720 (RD/YE) For Voltage
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes : GO to L3.

No : VERIFY the smart junction box (SJB) fuse 16 (15A) is OK. If OK, REPAIR the circuit. TEST the system for normal operation.
L3 CHECK CIRCUIT 694 (BK/LG) FOR AN OPEN
- Measure the resistance between the subwoofer amplifier C466-2, circuit 694 (BK/LG), harness side and ground.
  
  Fig 3: Checking Circuit 694 (BK/LG) For An Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to L4.

No : REPAIR the circuit. TEST the system for normal operation.
L4 CHECK FOR AN OUTPUT SIGNAL FROM THE AUDIO UNIT
- Key in ON position.
- Turn the audio unit on.
- Measure the AC voltage between the subwoofer amplifier C466-7, circuit 169 (LG/BK), harness side and the subwoofer amplifier C466-8, circuit 172 (LB/RD), harness side.
  
  Fig 4: Checking For An Output Signal From Audio Unit
  Courtesy of FORD MOTOR CO.
- Is there a fluctuating AC voltage?
Yes : REMOVE the subwoofer amplifier. REFER to SUBWOOFER AMPLIFIER in this article. SEND it to an authorized audio system repair facility. TEST the system for normal operation after the repair.

No : GO to L5.

L5 CHECK CIRCUITS 172 (LB/RD) AND 169 (LG/BK) FOR AN OPEN OR SHORT TO GROUND

Key in OFF position.
Disconnect: Audio Unit C229d.

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 CONNECTOR-PIN REFERENCE

Subwoofer Amplifier Connector-Pin	Audio Unit Connector-Pin	Circuit
C466-7	C229d-1	169 (LG/BK)
C466-8	C229d-2	172 (LB/RD)

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 audio system repair facility. TEST the system for normal operation after the repair.

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

L6 CHECK CIRCUIT 174 (GY/BK) FOR AN OPEN
- Key in OFF position.
- Disconnect: Audio Unit C229d.
- Measure the resistance between the audio unit C229d-3, circuit 174 (GY/BK), harness side and the subwoofer amplifier C466-1, circuit 174 (GY/BK), harness side; and between the audio unit C229d-3, circuit 174 (GY/BK), harness side and ground.
  
  Fig 5: Checking Circuit 174 (GY/BK) For An Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms between the connectors, and greater than 10,000 ohms between the audio unit and ground?
Yes : SEND the audio unit to an authorized audio system repair facility. TEST the system for normal operation after the repair.

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