Ford Mustang Service Manual: Entertainment System - General Information

Audio System (Diagnosis and Testing)

Refer to Wiring Diagrams Cell 130 , Radio for schematic and connector information.

Special Tool(s)


73III Automotive Meter 73III Automotive Meter 105-R0057 or equivalent

Inspection and Verification

1. Verify the customer concern by operating the electronic audio system with the engine running.

2. Visually inspect the following for obvious signs of mechanical and electrical damage.

Visual Inspection Chart

Mechanical

Electrical

  • Audio unit

  • Antenna or antenna cable

  • Speakers mounting/speaker cones

  • Radio ignition interference capacitor, radio frequency interference suppression bond or radio receiver hood bonding strap cleanliness

  • Battery junction box (BJB) fuses:
  • 3 (40A)
  • 4 (40A)
  • 6 (40A)
  • Central junction box (CJB) fuses:
  • 6 (20A)
  • 27 (25A)
  • 32 (15A)
  • Ignition switch
  • Circuitry
  • Audio unit

3. If the concern remains and the fault is not detected, proceed to the Symptom Chart to continue diagnostics.

Symptom Chart

Condition Possible Sources Action
  • The audio unit is inoperative/does not operate correctly
  • Central junction box (CJB) fuses:
  • 6 (20A).
  • 27 (25A).
  • 32 (15A).
  • Battery junction box (BJB) fuses:
  • 3 (40A).
  • 4 (40A).
  • 6 (40A).
  • Circuitry.
  • Audio unit.
  • Ignition switch.
  • Go To Pinpoint Test A .
  • Audio unit display blank - audio unit operates
  • Audio unit.
  • REMOVE the audio unit and SEND it to an authorized Ford audio system repair facility. TEST the system for normal operation.
  • Tape player only inoperative
  • Audio unit.
  • REMOVE the audio unit and SEND it to an authorized Ford audio system repair facility. TEST the system for normal operation.
  • Poor reception
  • Antenna connections.
  • Antenna cable.
  • Noise suppression equipment.
  • Audio unit.
  • Generator.
  • Ignition system.
  • Go To Pinpoint Test B .
  • Poor reception - FM only
  • FM signal out of range.
  • INFORM customer of methods for obtaining best reception.
  • Continuous SEEK/SCAN in AM/FM
  • Antenna.
  • Antenna connections.
  • Audio unit.
  • Go To Pinpoint Test C .
  • No sound from one or more of the speakers - not all speakers
  • Speaker(s).
  • Circuitry.
  • Audio unit.
  • Subwoofer amplifier
  • Go To Pinpoint Test D .
  • No sound from all of the speakers
  • Audio unit
  • Subwoofer amplifier.
  • Circuitry
  • Go To Pinpoint Test E .
  • Poor quality sound from one or more speakers (not all speakers)
  • Speaker(s).
  • Circuitry.
  • Audio unit.
  • Subwoofer amplifier.
  • Go To Pinpoint Test F
  • Poor quality sound from all speakers
  • Audio unit.
  • Speaker(s).
  • Circuitry
  • Go To Pinpoint Test G .
  • The subwoofer is inoperative
  • Subwoofer.
  • Subwoofer amplifier.
  • Circuitry.
  • Go To Pinpoint Test H .
  • Loud popping when cycling the ignition switch
  • Audio unit.
  • Circuitry
  • Go To Pinpoint Test I .
  • One or more audio control buttons (such as volume, seek, tune and scan) are not functional in either radio, tape, or CD mode or all modes
  • Audio unit.
  • REMOVE the audio unit and SEND it to an authorized Ford audio system repair facility. TEST the system for normal operation.
  • When the headlamp switch is in park or headlamp position and the ignition switch is in the RUN or ACC position, the audio unit back lighting is inoperative - all other I/P lighting functions are normal
  • Circuitry.
  • Audio unit.
  • REFER to Section
  • The audio unit has two items that can be dimmed-the audio unit display and the control buttons; one dims and the other does not
  • Audio unit.
  • REMOVE the audio unit and SEND it to an authorized Ford audio system repair facility. TEST the system for normal operation.
  • Irregular operation of display and indicator LEDs
  • Audio unit.
  • REMOVE the audio unit and SEND it to an authorized Ford audio system repair facility. TEST the system for normal operation.
  • Response time between pressing any of the audio control buttons and system response is more than two seconds
  • Audio unit.
  • REMOVE the audio unit and SEND it to an authorized Ford audio system repair facility. TEST the system for normal operation.

Pinpoint Tests

PINPOINT TEST A: THE AUDIO UNIT IS INOPERATIVE/DOES NOT OPERATE CORRECTLY

Test Step Result / Action to Take
A1 CHECK OPERATION OF THE AUDIO UNIT Yes

GO to A2 .

No

GO to A4

  • Key in ON position.
  • Turn on the audio unit.
  • Is the audio unit display illuminated?
A2 CHECK FOR SOUND COMING FROM THE SPEAKERS Yes

GO to A3 .

No

GO to Pinpoint Test C .

  • Verify that sound is coming from all the speakers.
  • Is there sound coming from all the speakers?
A3 CHECK THE AUDIO UNIT CONTROLS AND FEATURES Yes

System operation is normal at this time.

No

REMOVE the audio unit and SEND it to an authorized Ford audio system facility.

TEST the system for normal operation.

  • Refer to the owner literature for audio system controls.
  • Verify that the controls and features operate correctly.
  • Do the controls and features operate correctly?
A4 CHECK VOLTAGE AT THE AUDIO UNIT Yes

GO to A5 .

No

REPAIR the circuit (s) in question. TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: Audio Unit C290b.
  • Key in ON position.
  • Measure the voltage between the audio unit C290b pin 10, circuit 1002 (BK/PK), harness side and ground, and between the audio unit C290b pin 9, circuit 828 (VT/LB), harness side and ground.


  • Are the voltages greater than 10 volts?
A5 CHECK THE GROUND CIRCUITS TO THE AUDIO UNIT Yes

REMOVE the audio unit and SEND it to an authorized Ford audio system repair facility. TEST the system for normal operation.

No

REPAIR the circuit (s) in question. TEST the system for normal operation.

  • Key in OFF position.
  • Measure the resistance between the audio unit C290b pin 2, circuit 1205 (BK), harness side and ground; and between the audio unit C290b pin 11, circuit 694 (BK/LG), harness side and ground; and between the audio unit C290b pin 16, circuit 694 (BK/LG), harness side and ground


  • Are the resistances less than 5 ohms?

PINPOINT TEST B: POOR RECEPTION

Test Step Result / Action to Take
B1 CHECK ANTENNA CABLE CONNECTIONS Yes

GO to B2 .

No

CLEAN and SECURE the antenna connections as necessary. TEST the system for normal operation.

  • Key in OFF position.
  • Check the antenna connections including the extension cable.
  • Check to make sure the antenna is securely mounted to the vehicle body at ground points.
  • Are the connections clean, secure, and in metal-to-metal contact
B2 CHECK SUPPRESSION EQUIPMENT/MOUNTING AND CONNECTING CIRCUITS Yes

GO to B3 .

No

CLEAN, SECURE, or INSTALL new suppression equipment as necessary. TEST the system for normal operation

  • Check all necessary suppression equipment and the radio frequency interference suppression bond. Refer to Section
  • Check the radio receiver hood bonding strap and the body-to-chassis straps for integrity, cleanliness, and metal-tometal contact.
  • NOTE: The capacitor mounting points are used to complete the electrical circuit and must be mounted securely to clean surfaces.
  • Check the mounting and connecting circuits of the radio ignition interference capacitor for integrity, cleanliness, and metal-to-metal contact.
  • Are the connections clean, secure, and in metal-to-metal contact?
B3 CHECK RADIO IGNITION INTERFERENCE CAPACITOR Yes

INSTALL a new radio ignition interference capacitor. TEST the system for normal operation.

No

GO to B4 .

  • Check the operation of the radio ignition interference capacitor by substituting it with a known good component.
  • Key in START position.
  • Turn the audio unit on and check the radio reception.
  • Is the noise eliminated?
B4 CHECK GENERATOR Yes

INSTALL a new generator. REFER to Section . TEST the system for normal operation.

No

GO to B5 .

  • Key in OFF position.
  • Check the generator by disconnecting the wiring from the voltage regulator.
  • Key in START position.
  • Turn on the audio unit and check the radio reception.
  • Is the noise eliminated?
B5 CHECK IGNITION CIRCUITS Yes

GO to B6 .

No

REPAIR the ignition system as necessary. TEST the system for normal operation.

  • Key in OFF position.
  • Check the ignition circuits for correct routing, grounding, and integrity of connections.
  • Are the ignition components OK?
B6 SUBSTITUTE ANTENNA Yes

INSTALL a new antenna. TEST the system for normal operation.

No

GO to B7 .

  • Substitute a known good antenna.

    Ground the antenna base to an unpainted metal surface on the vehicle.

  • Key in START position.
  • Verify the operation of the audio unit.
  • Is the noise eliminated?
B7 SUBSTITUTE ANTENNA CABLE Yes

INSTALL a new antenna cable. TEST the system for normal operation.

No

GO to B8 .

  • Key in OFF position.
  • Substitute a known good antenna cable.
  • Key in START position.
  • Verify the operation of the audio unit.
  • Is the noise eliminated?
B8 SUBSTITUTE AUDIO UNIT Yes

REMOVE the audio unit and SEND it to an authorized Ford audio system repair facility.

TEST the system for normal operation.

No

GO to B9 .

  • Key in OFF position.
  • Substitute a known good audio unit.
  • Key in START position.
  • Verify the operation of the audio unit.
  • Is the noise eliminated?
B9 SUBSTITUTE SUBWOOFER AMPLIFIER Yes

REMOVE the subwoofer amplifier and SEND it to an authorized Ford audio system repair facility.

TEST the system for normal operation.

No

GO to B10 .

  • Key in OFF position.
  • Substitute a known good subwoofer amplifier.
  • Key in START position.
  • Verify the operation of the audio unit.
  • Is the noise eliminated?
B10 REPOSITION COMPONENTS Yes

Permanently REPOSITION the components as needed. TEST the system for normal operation.

No

GROUND various parts (for example, engine, fenders, quarter panels, stone deflectors, body sheet metal) of the vehicle to the frame using a jumper cable. When noise is eliminated, PROVIDE a permanent ground where necessary. TEST the system for normal operation.

  • Key in OFF position.
  • Determine if the noise can be eliminated by repositioning the antenna cable, speaker circuits, or audio unit power feed circuits away from other circuits or brackets.
  • Key in START position.
  • Verify the operation of the audio unit.
  • Is the noise eliminated?

PINPOINT TEST C: CONTINUOUS SEEK/SCAN IN AM/FM

Test Step Result / Action to Take
C1 CHECK OPERATION OF THE SEEK/SCAN FUNCTIONS Yes

GO to C2 .

No

The system is OK.

  • Key in ON position.
  • Operate the SEEK/SCAN functions with the audio unit in both AM and FM tuner modes.
  • Do the SEEK/SCAN functions search continuously?
C2 CHECK ANTENNA FOR DAMAGE Yes

GO to C3 .

No

REPAIR the antenna. REFER to Section

  • Key in OFF position.
  • Disconnect: Antenna Lead Terminal.
  • Measure the resistance between the antenna cable lead terminal and the end of the antenna grid wire.
  • Is the resistance less than 8 ohms?
C3 SUBSTITUTE ANTENNA EXTENSION CABLE Yes

INSTALL a new antenna extension cable. REFER to Section. TEST the system for normal operation.

No

REINSTALL the original cable. REMOVE the audio unit and SEND it to an authorized Ford audio system repair facility. TEST the system for normal operation.

  • Substitute a known good antenna cable between the audio unit and the antenna.
  • Key in START position.
  • Check the operation of the audio unit.
  • Is the noise eliminated?

PINPOINT TEST D: NO SOUND FROM ONE OR MORE OF THE SPEAKERS - NOT ALL SPEAKERS

Test Step Result / Action to Take
D1 CHECK FOR SOUND Yes

GO to Pinpoint Test E .

No

For convertible, GO to D2 .

For coupe, GO to D4 .

For Mach 1000 subwoofer speakers,GO to D8 .

  • Key in ON position.
  • Turn on the audio unit.
  • Are all speakers without sound?
D2 CHECK CIRCUITS BETWEEN THE AFFECTED SPEAKER(S) AND SUBWOOFER AMPLIFIERS Yes

GO to D3 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Disconnect: Subwoofer Amplifier C4108a.
  • Disconnect: Subwoofer Amplifier C4109b.
  • Disconnect: Affected Speaker(s).
  • Measure the resistance between the subwoofer amplifier and the affected speaker(s) and between the subwoofer amplifier and ground as follows:

Speaker Circuits


  • Are the resistances less than 5 ohms between the subwoofer amplifier and the affected speaker(s) and greater than 10,000 ohms between the subwoofer amplifier and ground?
D3 CHECK CIRCUITS BETWEEN THE AUDIO UNIT AND THE SUBWOOFER AMPLIFIERS Yes

GO to D6 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation

  • Disconnect: Audio Unit C290b.
  • Disconnect: Subwoofer Amplifier C4108a.
  • Disconnect: Subwoofer Amplifier C4109b.
  • Measure the resistance between the subwoofer amplifier and the audio unit C290b and between the subwoofer amplifier and ground as follows:

Speaker Circuits


  • Are the resistances less than 5 ohms between the subwoofer amplifier and the audio unit and greater than 10,000 ohms between the subwoofer amplifier and ground?
D4 CHECK CIRCUITS BETWEEN THE AFFECTED SPEAKER(S) AND SUBWOOFER AMPLIFIER Yes

GO to D5 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Disconnect: Subwoofer Amplifier C4109b.
  • Disconnect: Affected Speaker(s).
  • Measure the resistance between the subwoofer amplifier and the affected speaker(s) and between the subwoofer amplifier and ground as follows:

Speaker Circuits


  • Are the resistances less than 5 ohms between the subwoofer amplifier and affected speaker(s) and greater than 10,000 ohms between the subwoofer amplifier and ground?
D5 CHECK CIRCUITS BETWEEN THE AUDIO UNIT AND THE SUBWOOFER AMPLIFIER Yes

GO to D6 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Disconnect: Audio Unit C290b.
  • Disconnect: Subwoofer Amplifier C4109b.
  • Measure the resistance between the subwoofer amplifier C4109b pin 5, circuit 169 (LG/BK), harness side and the audio unit C290a pin 6, circuit 169 (LG/BK), harness side and between the subwoofer amplifier C4109b pin 5, circuit 169 (LG/BK), harness side and ground; and between the subwoofer amplifier C4109b pin 6, circuit 172 (LB/RD), harness side and the audio unit C290a pin 5, circuit 172 (LB/RD), harness side and between the subwoofer amplifier C4109b pin 6, circuit 172 (LB/RD), harness side and ground.
  • Are the resistances less than 5 ohms between the subwoofer amplifier and the audio unit and greater than 10,000 ohms between the subwoofer amplifier and ground?
D6 CHECK SPEAKER(S) Yes

INSTALL a new speaker. TEST the system for normal operation.

No

GO to D7 .

  • Key in OFF position.
  • Substitute the affected speaker with a known good component.
  • Key in ON position.
  • Turn on the audio unit.
  • Is the affected speaker(s) operational?
D7 CHECK THE AUDIO UNIT Yes

SEND the audio unit to an authorized Ford audio system repair facility.

TEST the system for normal operation.

No

REMOVE the subwoofer amplifier and SEND it to an authorized Ford audio system repair facility.

TEST the system for normal operation.

  • Key in OFF position.
  • Substitute the affected audio unit with a known good component.
  • Key in ON position.
  • Turn on the audio unit.
  • Is the affected speaker(s) operational?
D8 CHECK FOR POWER TO THE AFFECTED SUBWOOFER AMPLIFIER Yes

GO to D9 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: Mach 1000 Affected Subwoofer Amplifier.
  • Measure the voltage between affected subwoofer amplifier pin 5, circuit 828 (VT/LB) (left amplifiers) and ground, or between pin 5, circuit 829 (WH/VT) (right amplifiers) and ground.


  • Is the voltage greater than 10 volts?
D9 CHECK FOR GROUND TO THE AFFECTED SUBWOOFER AMPLIFIER Yes

GO to D10 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • NOTE: Ground circuit 694 is located in the same cavity in all four subwoofer amplifiers.
  • Measure the resistance between affected subwoofer amplifier pin 2, circuit 694 (BK/LG) and ground.


  • Is the resistance less than 5 ohms?
D10 CHECK FOR AN AUDIO SIGNAL TO THE AFFECTED SUBWOOFER AMPLIFIER Yes

GO to D12 .

No

GO to D11 .

  • Key in ON position.
  • NOTE: Audio signal circuits 169 and 172 are located in the same cavity on all four subwoofer amplifiers.
  • Turn on the audio unit and check for a fluctuating AC voltage between affected subwoofer amplifier pin 8, circuit 172 (LB/RD) and pin 7, circuit 169 (LG/BK).


  • Does the voltage vary as the volume is adjusted?
D11 CHECK AUDIO SIGNAL CIRCUITS AT THE AFFECTED SUBWOOFER AMPLIFIER FOR OPEN AND SHORT TO GROUND Yes

SEND the audio unit to an authorized Ford audio system repair facility.

TEST the system for normal operation.

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: Audio Unit C290a.
  • Measure the resistance between the affected subwoofer amplifier and the audio unit C290a, and between the affected subwoofer amplifier and ground as follows:

Speaker Circuits


  • Is the resistance less than 5 ohms between the audio unit and subwoofer amplifier and greater that 10,000 ohms between the subwoofer amplifier and ground?
D12 CHECK FOR AN AUDIO SIGNAL AT THE AFFECTED SUBWOOFER Yes

INSTALL a new subwoofer speaker.

No

GO to D13 .

  • Key in OFF position.
  • Connect: Affected Subwoofer Amplifier.
  • Disconnect: Affected Subwoofer Speaker .
  • Key in ON position.
  • Turn on the audio unit and check for a fluctuating AC voltage between affected subwoofer as follows: For right subwoofer pin 4, circuit 187 (DB/OG) and pin 2, circuit 189 (LG/BK) harness side; and between pin 3, circuit 179 (OR/RD) and pin 1, circuit 176 (PK/LG) harness side. For left subwoofer pin 1, circuit 187 (DB/OR) and pin 3, circuit 189 (LG/BK) harness side; and between pin 2, circuit 179 (OR/RD) and pin 4, circuit 176 (PK/LG) harness side.


  • Does the voltage vary as the volume is adjusted?
D13 CHECK FOR AN OPEN AND SHORT TO GROUND BETWEEN THE AFFECTED SUBWOOFER AND ITS RESPECTIVE AMPLIFIERS Yes

INSTALL a new subwoofer amplifier.

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: Respective Amplifier to Subwoofer Speaker Connector.
  • Measure the resistance between the affected subwoofer speaker and its respective amplifiers, and between the affected subwoofer speaker and ground as follows:

Speaker Circuits-Right Side

Speaker Circuits-Left Side


Speaker Circuits-Left Side


  • Is the resistance less than 5 ohms between the amplifier and subwoofer speaker and greater that 10,000 ohms between the subwoofer speaker harness and ground?

PINPOINT TEST E: NO SOUND FROM ALL OF THE SPEAKERS

Test Step Result / Action to Take
E1 CHECK FOR AUDIO UNIT OPERATION Yes

GO to E2 .

No

GO to Pinpoint Test A .

  • Key in ON position.
  • Turn the audio unit on.
  • Does the audio unit display illuminate?
E2 CHECK THE SPEAKER OPERATION Yes

REMOVE the audio unit and SEND it to an authorized Ford audio system repair facility. TEST the system for normal operation.

No

GO to Pinpoint Test D .

  • Check the operation of all speakers.
  • Are all speakers inoperative?

PINPOINT TEST F: POOR QUALITY SOUND FROM ONE OR MORE SPEAKERS (NOT ALL SPEAKERS)

Test Step Result / Action to Take
F1 CHECK SOUND QUALITY Yes

REMOVE the audio unit and SEND it to an authorized Ford audio system repair facility.

TEST the system for normal operation.

No

For convertible, GO to F2 .

For coupe, GO to F4 .

For Mach 1000 subwoofer speakers,GO to F6 .

  • Key in ON position.
  • Turn on the audio unit.
  • Carry out the speaker walk-around test by pressing preset buttons 3 and 6 simultaneously.
  • Do all speakers have poor sound quality?
F2 CHECK CIRCUITS BETWEEN AFFECTED SPEAKER(S) AND SUBWOOFER AMPLIFIERS Yes

GO to F3 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Disconnect: Subwoofer Amplifier C4108a.
  • Disconnect: Subwoofer Amplifier C4109b.
  • Disconnect: Affected Speaker(s).
  • Measure the resistance between the subwoofer amplifier and the affected speaker(s) and between subwoofer amplifier and ground as follows:

Speaker Circuits


  • Are the resistances less than 5 ohms between the subwoofer amplifier and the affected speaker(s) and greater than 10,000 ohms between the subwoofer amplifier and ground?
F3 CHECK CIRCUITS BETWEEN THE AUDIO UNIT AND THE SUBWOOFER AMPLIFIERS Yes

GO to F6 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Disconnect: Audio Unit C290b.
  • Disconnect: Subwoofer Amplifier C4108b.
  • Disconnect: Subwoofer Amplifier C4109b.
  • Measure the resistance between subwoofer amplifier and audio unit C290a and between subwoofer amplifier and ground as follows:

Speaker Circuits


  • Are the resistances less than 5 ohms between the subwoofer amplifier and the audio unit and greater than 10,000 ohms between the subwoofer amplifier and ground?
F4 CHECK CIRCUITS BETWEEN AFFECTED SPEAKER(S) AND SUBWOOFER AMPLIFIER Yes

GO to F5 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Disconnect: Subwoofer Amplifier C4109b.
  • Disconnect: Affected Speaker(s).
  • Measure the resistance between subwoofer amplifier and the affected speaker(s) and between subwoofer amplifier and ground as follows:

Speaker Circuits


  • Are the resistances less than 5 ohms between the subwoofer amplifier and the affected speaker(s) and greater than 10,000 ohms between the subwoofer amplifier and ground?
F5 CHECK CIRCUITS BETWEEN THE AUDIO UNIT AND THE SUBWOOFER AMPLIFIER Yes

GO to F10 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Disconnect: Audio Unit C290b.
  • Disconnect: Subwoofer Amplifier C4109b.
  • Measure the resistance between the subwoofer amplifier C4109b pin 5, circuit 169 (LG/BK), harness side and the audio unit C290a pin 6, circuit 169 (LG/BK), harness side and between the subwoofer amplifier C4109b pin 5, circuit 169 (LG/BK), harness side and ground; and between the subwoofer amplifier C4109b pin 6, circuit 172 (LB/RD), harness side and the audio unit C290a pin 5, circuit 172 (LB/RD), harness side and between the subwoofer amplifier C4109b pin 6, circuit 172 (LB/RD), harness side and ground.
  • Are the resistances less than 5 ohms between the subwoofer amplifier and the audio unit and greater than 10,000 ohms between the subwoofer amplifier and ground?
F6 CHECK FOR AN AUDIO SIGNAL TO THE SUBWOOFER AMPLIFIER HARNESS Yes

GO to F8 .

No

GO to F7 .

  • Key in OFF position.
  • Disconnect: Mach 1000 Affected Subwoofer Amplifier.
  • Key in ON position.
  • NOTE: Audio signal circuits 169 and 172 are located in the same cavity on all four subwoofers.
  • Turn on the audio unit and check for a fluctuating AC voltage between affected subwoofer amplifier pin 8, circuit 172 (LB/RD) and pin 7, circuit 169 (LG/BK).


  • Does the voltage vary as the volume is adjusted?
F7 CHECK AUDIO SIGNAL CIRCUITS AT THE AFFECTED SUBWOOFER AMPLIFIER FOR OPEN AND SHORT TO GROUND Yes

SEND the audio unit to an authorized Ford audio system repair facility.

TEST the system for normal operation.

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: Audio Unit C290a.
  • Measure the resistance between the affected subwoofer amplifier and the audio unit C290a and between the affected subwoofer amplifier and ground as follows:

Speaker Circuits


  • Is the resistance less than 5 ohms between the audio unit and subwoofer amplifier harness and greater that 10,000 ohms between the subwoofer amplifier harness and ground?
F8 CHECK FOR AN AUDIO SIGNAL AT THE AFFECTED SUBWOOFER Yes

INSTALL a new subwoofer speaker

No

GO to F9

  • Key in OFF position.
  • Connect: Affected Subwoofer Amplifier.
  • Disconnect: Affected Subwoofer Speaker.
  • Key in ON position.
  • Turn on the audio unit and check for a fluctuating AC voltage between affected subwoofer as follows: For right subwoofer pin 4, circuit 187 (DB/OG) and pin 2, circuit 189 (LG/BK) harness side; and between pin 3, circuit 179 (OR/RD) and pin 1, circuit 176 (PK/LG) harness side. For left subwoofer pin 1, circuit 187 (DB/OR) and pin 3, circuit 189 (LG/BK) harness side; and between pin 2, circuit 179 (OR/RD) and pin 4, circuit 176 (PK/LG) harness side.


  • Does the voltage vary as the volume is adjusted?
F9 CHECK FOR AN OPEN AND SHORT TO GROUND BETWEEN THE AFFECTED SUBWOOFER AND ITS RESPECTIVE AMPLIFIERS Yes

INSTALL a new subwoofer amplifier.

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: Affected Subwoofer.
  • Disconnect: Respective Amplifier.
  • Measure the resistance between the affected subwoofer speaker and its respective amplifiers, and between the affected subwoofer speaker and ground as follows:

Speaker Circuits-Right Side

Speaker Circuits-Left Side


Speaker Circuits-Left Side


  • Is the resistance less than 5 ohms between the amplifier and subwoofer speaker and greater that 10,000 ohms between the subwoofer speaker harness and ground?
F10 CHECK SPEAKER(S) Yes

INSTALL a new speaker. TEST the system for normal operation.

No

GO to F7 .

  • Key in OFF position.
  • Substitute the affected speaker with a known good component.
  • Key in ON position
  • Turn on the audio unit.
  • Is the sound quality OK?
F11 CHECK THE AUDIO UNIT Yes

SEND the audio unit to an authorized Ford audio system repair facility.

TEST the system for normal operation.

No

REMOVE the subwoofer amplifier and SEND it to an authorized Ford audio system repair facility.

TEST the system for normal operation.

  • Key in OFF position.
  • Substitute the affected audio unit with a known good component.
  • Key in ON position.
  • Turn on the audio unit.
  • Is the sound quality OK?

PINPOINT TEST G: POOR QUALITY SOUND FROM ALL SPEAKERS

Test Step Result / Action to Take
G1 CHECK POOR SOUND QUALITY IN ALL SPEAKERS Yes

REMOVE the audio unit and SEND it to an authorized Ford audio system repair facility.

TEST the system for normal operation.

No

GO to Pinpoint Test F .

  • Key in ON position.
  • Turn on the audio unit.
  • Carry out the speaker walk-around test by pressing preset buttons 3 and 6 simultaneously.
  • Is there poor quality or distortion in all speakers?

PINPOINT TEST H: THE SUBWOOFER IS INOPERATIVE

Test Step Result / Action to Take
H1 CHECK THE SUBWOOFER OPERATION Yes

GO to H16 .

No

For convertible, GO to H2 .

For coupe, GO to H6 .

For Mach 1000 subwoofer speakers,GO to H10 .

  • Key in ON position.
  • Turn on the audio unit and listen for correct subwoofer operation.
  • Are all subwoofers inoperative?
H2 CHECK POWER TO THE SUBWOOFER AMPLIFIERS Yes

GO to H3 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: LH Subwoofer Amplifier C4108a.
  • Disconnect: RH Subwoofer Amplifier C4109b.
  • Key in ON position.
  • Turn on the audio unit.
  • Measure the voltage between the subwoofer amplifiers pin 4, circuit 828 (VT/LB), harness side and ground; and between the subwoofer amplifiers pin 5, circuit 828 (VT/LB), harness side and ground; and between the subwoofer amplifiers pin 6, circuit 828 (VT/LB), harness side and ground.


  • Are the voltages greater than 10 volts?
H3 CHECK GROUND TO THE SUBWOOFER AMPLIFIERS Yes

GO to H4 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Measure the resistance between the subwoofer amplifiers C4108a (LH) or C4109a (RH) pin 1, circuit 694 (BK/LG), harness side and ground; and between the subwoofer amplifiers C4108a (LH) or C4109a (RH) pin 2, circuit 694 (BK/LG), harness side and ground; and between the subwoofer amplifiers C4108a (LH) or C4109a (RH) pin 3, circuit 694 (BK/LG), harness side and ground


  • Are the resistances less than 5 ohms?
H4 CHECK THE SUBWOOFER AMPLIFIER ENABLE CIRCUIT FOR POWER Yes

GO to H5 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: Subwoofer Amplifier C4109b.
  • Disconnect: Subwoofer Amplifier C4108b.
  • Key in ON position.
  • Turn the audio unit on.
  • Measure the voltage between the LH subwoofer amplifier C4108b pin 2, circuit 173 (DG/VT), harness side and ground; and between the RH subwoofer amplifier C4109b pin 2, circuit 174 (GY/BK), harness side and ground.


  • Is voltage indicated?
H5 CHECK THE AUDIO UNIT Yes

SEND the audio unit to an authorized Ford audio system repair facility.

TEST the system for normal operation.

No

REMOVE the subwoofer amplifier and SEND it to an authorized Ford audio system repair facility.

TEST the system for normal operation.

  • Substitute a known good audio unit.
  • Verify the operation of the audio unit.
  • Does the audio unit operate correctly?
H6 CHECK THE VOLTAGE TO THE SUBWOOFER AMPLIFIER Yes

GO to H7 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: Subwoofer Amplifier C4109b.
  • Key in ON position.
  • Turn on the audio unit.
  • Measure the voltage between the subwoofer amplifier C4109b pin 5, circuit 828 (VT/LB), harness side and ground; between the subwoofer amplifier C4109b pin 6, circuit 828 (VT/LB), harness side and ground; and between the subwoofer amplifier C4109b pin 7, circuit 828 (VT/LB), harness side and ground.


  • Are the voltages greater than 10 volts?
H7 CHECK THE GROUND TO THE SUBWOOFER AMPLIFIER Yes

GO to H8 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Measure the resistance between the subwoofer amplifier C4109b pin 1, circuit 694 (BK/LG), harness side and ground; between the subwoofer amplifier C4109b pin 2, circuit 694 (BK/LG), harness side and ground; and between the subwoofer amplifier C4109b pin 3, circuit 694 (BK/LG), harness side and ground.


  • Are the resistances less than 5 ohms?
H8 CHECK THE SUBWOOFER ENABLE CIRCUIT FOR POWER Yes

GO to H9 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: Subwoofer Amplifier C4109b.
  • Key in ON position.
  • With the audio unit turned on, measure the voltage between the subwoofer amplifier C4109b pin 2, circuit 173 (DG/VT), harness side and ground.


  • Is voltage indicated?
H9 CHECK CIRCUITS BETWEEN THE AUDIO UNIT AND THE SUBWOOFER AMPLIFIER Yes

GO to H10 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Disconnect: Audio Unit C290b.
  • Disconnect: Subwoofer Amplifier C4109b.
  • Measure the resistance between the subwoofer amplifier C4109b pin 5, circuit 169 (LG/BK), harness side and the audio unit C290a pin 6, circuit 169 (LG/BK), harness side and between the subwoofer amplifier C4109b pin 5, circuit 169 (LG/BK), harness side and ground; and between the subwoofer amplifier C4109b pin 6, circuit 172 (LB/RD), harness side and the audio unit C290a pin 5, circuit 172 (LB/RD), harness side and between the subwoofer amplifier C4109b pin 6, circuit 172 (LB/RD), harness side and ground.
  • Are the resistances less than 5 ohms between the subwoofer amplifier and the audio unit and greater than 10,000 ohms between the subwoofer amplifier and ground?
H10 CHECK FOR POWER TO THE AFFECTED SUBWOOFER AMPLIFIER Yes

GO to H11 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: Mach 1000 Affected Subwoofer Amplifier.
  • Measure the voltage between affected amplifier harness pins 1 and 2, circuit 828 (VT/LB) (left amplifiers) and ground, and between pins 4 and 5, circuit 829 (WH/VT) (right amplifiers) and ground.


  • Is the voltage greater than 10 volts?
H11 CHECK FOR GROUND TO THE SUBWOOFER AMPLIFIER HARNESS Yes

GO to H12 .

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • NOTE: Ground circuit 694 is located in the same cavity in all four subwoofer amplifiers.
  • Measure the resistance between subwoofer amplifier pins 2, circuit 694 (BK/LG) and ground.


  • Is the resistance less than 5 ohms?
H12 CHECK FOR AN AUDIO SIGNAL TO THE AFFECTED SUBWOOFER AMPLIFIER Yes

GO to H14 .

No

GO to H13 .

  • Key in ON position.
  • NOTE: Audio signal circuits 169 and 172 are located in the same cavity on all four subwoofers.
  • Turn on the audio unit and check for a fluctuating AC voltage between affected subwoofer amplifier pin 8, circuit 172 (LB/RD) and pin 7, circuit 169 (LG/BK).


  • Does the voltage vary as the volume is adjusted?
H13 CHECK AUDIO SIGNAL CIRCUITS AT THE AFFECTED SUBWOOFER AMPLIFIER FOR OPEN AND SHORT TO GROUND Yes

SEND the audio unit to an authorized Ford audio system repair facility.

TEST the system for normal operation.

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: Audio Unit C290a.
  • Measure the resistance between the affected subwoofer amplifier and the audio unit C290a, and between the affected subwoofer amplifier and ground as follows:

Speaker Circuits


  • Is the resistance less than 5 ohms between the audio unit and subwoofer amplifier harness and greater that 10,000 ohms between the subwoofer amplifier harness and ground?
H14 CHECK FOR AN AUDIO SIGNAL AT THE AFFECTED SUBWOOFER Yes

INSTALL a new subwoofer speaker.

No

GO to H15 .

  • Key in OFF position.
  • Connect: Affected Subwoofer Amplifier.
  • Disconnect: Affected Subwoofer Speaker.
  • Key in ON position.
  • Turn on the audio unit and check for a fluctuating AC voltage between affected subwoofer as follows: For right subwoofer pin 4, circuit 187 (DB/OG) and pin 2, circuit 189 (LG/BK) harness side; and between pin 3, circuit 179 (OR/RD) and pin 1, circuit 176 (PK/LG) harness side. For left subwoofer pin 1, circuit 187 (DB/OR) and pin 3, circuit 189 (LG/BK) harness side; and between pin 2, circuit 179 (OR/RD) and pin 4, circuit 176 (PK/LG) harness side.


  • Does the voltage vary as the volume is adjusted?
H15 CHECK FOR AN OPEN AND SHORT TO GROUND BETWEEN THE AFFECTED SUBWOOFER AND ITS RESPECTIVE AMPLIFIERS Yes

INSTALL a new subwoofer amplifier.

No

REPAIR the circuit (s) in question.

TEST the system for normal operation.

  • Key in OFF position.
  • Disconnect: Affected Subwoofer.
  • Disconnect: Respective Amplifier.
  • Measure the resistance between the affected subwoofer speaker and its respective amplifiers, and between the affected subwoofer speaker and ground as follows:

Speaker Circuits-Right Side


Speaker Circuits-Left Side


Speaker Circuits-Left Side


  • Is the resistance less than 5 ohms between the amplifier and subwoofer speaker and greater that 10,000 ohms between the subwoofer speaker harness and ground?
H16 CHECK THE AUDIO UNIT Yes

SEND the audio unit to an authorized Ford audio system repair facility.

TEST the system for normal operation.

No

REMOVE the subwoofer amplifier and SEND it to an authorized Ford audio system repair facility.

TEST the system for normal operation.

  • Substitute a known good audio unit.
  • Verify the operation of the audio unit.
  • Does the audio unit operate correctly?

PINPOINT TEST I: LOUD POPPING WHEN CYCLING THE IGNITION SWITCH-CONVERTIBLE

Test Step Result / Action to Take
I1 CHECK SUBWOOFERS FOR LOUD POPS Yes

REMOVE the audio unit and SEND it to an authorized Ford audio system repair facility.

TEST the system for normal operation

No

If the loud pops are from the convertible LH subwoofer amplifier only, REPAIR circuit 173 (DG/VT). TEST the system for normal operation.

If the loud pops are from the convertible RH subwoofer amplifier only, REPAIR circuit 174 (GY/BK). TEST the system for normal operation

  • Key in ON position.
  • Listen to see whether the loud pops are from the LH or RH subwoofer amplifiers for the convertible.
  • Are the pops from both subwoofer amplifiers for the convertible?

 

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