Ignition noise in car audio

[frankin]

The sound of the ignition is heard on all the car audio. Even when the engine is first started. It is rather aggravating, because it has rendered my stereo system useless.
Is there some kind of radio ignition interference capacitor somewhere? This just started a couple of weeks ago and I have been going crazy trying to locate it.

 

[boosted2000si]

Aftermarket or stock head unit? Any subs?

Alot of time that is caused by having the power to close to the ground wire.

 

[steedafever]

sounds like there is a bad ground wire or its not ground properly.

 

[frankin]

It is the stock 460. Where is a good place to start looking?

 

[boosted2000si]

If its all stock, man I wouldnt know where to start. Is the car under warranty by chance?

 

[steedafever]

me either, try behind the radio and see if anything is loose and follow the ground wire to it grounded spot and make sure its not loose

 

[speeddemon2000]

On the back of the heads there are some resistors for radio noise interference, make sure they are plugged in and still in place. Do you have any aftermarket wiring at all? If so that would be the first place to check. Also check the ground wire going from the frame to the engine. It connects to the motor mount. Make sure that hasn't come lose. Make sure the battery terminals are clean. Check your voltage. You should be putting out 14.0 volts at idle. If you are in the low 13's high 12's your alternator is on it's way out. Alternators go bad in these cars alot. If you have never replace one that could be the cause of your issue.

 

[sik02gt]

the stock stereos in these cars are such a pain in the ass, just everything about it all the wiring from ford is like completely ass backwards goed forbid someone wants change their speakers the type of project that can become, anyhow getting off track just as the guy above said check everything in the back of the head unit make sure that nothing has come loose other then that im not really sure as where else to start fuse maybe? idk if i were u i would completely re-do the stock stereo that shit sucks anyways

 

[Evil Bender]

I found that the ground behind the drivers kickpanel was loose and causing my ground hum.

 

[CobraBob]

Have you made any mods recently that might tie into this radio issue? I always suggest going back over was recently done to a car when an issue suddenly develops.

Does the noise vary in pitch or is it constant? If the noise varies, it is caused by something that varies its speed with the engine, like the ignition, the alternator or even a fuel injector. Constant-speed noises are usually caused by an electric motor (usually an electric fuel pump). Unfortunately, even though the noise comes from a radio speaker, it may be caused by any manner of device anywhere on your vehicle and not even related to the radio. Best of luck finding the bugger!

 

[hotcobra03]

check grounds and fuses

here is fords rundown on radio ........................................................................................................................SECTION 415-00: Entertainment System — General Information 2003 Mustang Workshop Manual
DIAGNOSIS AND TESTING Procedure revision date: 03/18/2002

--------------------------------------------------------------------------------

Audio System Printable View (130 KB)
Refer to Wiring Diagrams Cell 130 , Radio for schematic and connector information.


Special Tool(s) 73III Automotive Meter
105-R0057 or equivalent


Inspection and Verification

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



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

Symptom Chart

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 413-00 .

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
Key in ON position.
Turn on the audio unit.
Is the audio unit display illuminated?
Yes
GO to A2 .

No
GO to A4 .
A2 CHECK FOR SOUND COMING FROM THE SPEAKERS
Verify that sound is coming from all the speakers.
Is there sound coming from all the speakers?
Yes
GO to A3 .

No
GO to Pinpoint Test C .
A3 CHECK THE AUDIO UNIT CONTROLS AND FEATURES
Refer to the owner literature for audio system controls.
Verify that the controls and features operate correctly.
Do the controls and features operate correctly?
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.
A4 CHECK VOLTAGE AT THE AUDIO UNIT
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?
Yes
GO to A5 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
A5 CHECK THE GROUND CIRCUITS TO THE AUDIO UNIT
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?
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.

PINPOINT TEST B: POOR RECEPTION
Test Step Result / Action to Take
B1 CHECK ANTENNA CABLE CONNECTIONS
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?
Yes
GO to B2 .

No
CLEAN and SECURE the antenna connections as necessary. TEST the system for normal operation.
B2 CHECK SUPPRESSION EQUIPMENT/MOUNTING AND CONNECTING CIRCUITS
Check all necessary suppression equipment and the radio frequency interference suppression bond. Refer to Section 415-01 .
Check the radio receiver hood bonding strap and the body-to-chassis straps for integrity, cleanliness, and metal-to-metal 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?
Yes
GO to B3 .

No
CLEAN, SECURE, or INSTALL new suppression equipment as necessary. TEST the system for normal operation.
B3 CHECK RADIO IGNITION INTERFERENCE CAPACITOR
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?
Yes
INSTALL a new radio ignition interference capacitor. TEST the system for normal operation.

No
GO to B4 .
B4 CHECK GENERATOR
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?
Yes
INSTALL a new generator. REFER to Section 414-02 . TEST the system for normal operation.

No
GO to B5 .
B5 CHECK IGNITION CIRCUITS
Key in OFF position.
Check the ignition circuits for correct routing, grounding, and integrity of connections.
Are the ignition components OK?
Yes
GO to B6 .

No
REPAIR the ignition system as necessary. TEST the system for normal operation.
B6 SUBSTITUTE ANTENNA
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?
Yes
INSTALL a new antenna. TEST the system for normal operation.

No
GO to B7 .
B7 SUBSTITUTE ANTENNA CABLE
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?
Yes
INSTALL a new antenna cable. TEST the system for normal operation.

No
GO to B8 .
B8 SUBSTITUTE AUDIO UNIT
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?
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 .
B9 SUBSTITUTE SUBWOOFER AMPLIFIER
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?
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 .
B10 REPOSITION COMPONENTS
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?
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.

PINPOINT TEST C: CONTINUOUS SEEK/SCAN IN AM/FM
Test Step Result / Action to Take
C1 CHECK OPERATION OF THE SEEK/SCAN FUNCTIONS
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?
Yes
GO to C2 .

No
The system is OK.
C2 CHECK ANTENNA FOR DAMAGE
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?
Yes
GO to C3 .

No
REPAIR the antenna. REFER to Section 415-02
C3 SUBSTITUTE ANTENNA EXTENSION CABLE
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?
Yes
INSTALL a new antenna extension cable. REFER to Section 415-02 . 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.

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
Key in ON position.
Turn on the audio unit.
Are all speakers without 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 .
D2 CHECK CIRCUITS BETWEEN THE AFFECTED SPEAKER(S) AND SUBWOOFER AMPLIFIERS
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 Affected Speaker Pin Subwoofer Amplifier Pin Circuit
RF 1 (convertible only) LH 7 822 (BK/LG)
RF 2 (convertible only) LH 8 287 (BK/WH)
LF 1 (convertible only) LH 7 822 (BK/LG)
LF 2 (convertible only) LH 8 287 (BK/WH)
RR 1 RH 7 822 (BK/LG)
RR 2 RH 8 287 (BK/WH)
LR 1 RH 7 822 (BK/LG)
LR 2 RH 8 287 (BK/WH)


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?
Yes
GO to D3 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
D3 CHECK CIRCUITS BETWEEN THE AUDIO UNIT AND THE SUBWOOFER AMPLIFIERS
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 Audio Unit C290b Pin Subwoofer Amplifier Pin Circuit
2 LH 5 167 (BN/OG)
6 RH 5 169 (LG/BK)
1 LH 6 168 (RD/BK)
5 RH 6 172 (LB/RD)


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?
Yes
GO to D6 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
D4 CHECK CIRCUITS BETWEEN THE AFFECTED SPEAKER(S) AND SUBWOOFER AMPLIFIER
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 Affected Speaker Pin Subwoofer Amplifier Pin Circuit
RR 1 7 822 (BK/LG)
RR 2 8 287 (BK/WH)
LR 1 7 822 (BK/LG)
LR 2 8 287 (BK/WH)


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?
Yes
GO to D5 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
D5 CHECK CIRCUITS BETWEEN THE AUDIO UNIT AND THE SUBWOOFER AMPLIFIER
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?
Yes
GO to D6 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
D6 CHECK SPEAKER(S)
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?
Yes
INSTALL a new speaker. TEST the system for normal operation.

No
GO to D7 .
D7 CHECK THE AUDIO UNIT
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?
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.
D8 CHECK FOR POWER TO THE AFFECTED SUBWOOFER AMPLIFIER
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?
Yes
GO to D9 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
D9 CHECK FOR GROUND TO THE AFFECTED SUBWOOFER AMPLIFIER
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?
Yes
GO to D10 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
D10 CHECK FOR AN AUDIO SIGNAL TO THE AFFECTED SUBWOOFER AMPLIFIER
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?
Yes
GO to D12 .

No
GO to D11 .
D11 CHECK AUDIO SIGNAL CIRCUITS AT THE AFFECTED SUBWOOFER AMPLIFIER FOR OPEN AND SHORT TO GROUND
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 Audio Unit C290a Pin Subwoofer Amplifier Pin Circuit
2 8 172 (LB/RD)
8 7 169 (LG/BK)


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?
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.
D12 CHECK FOR AN AUDIO SIGNAL AT THE AFFECTED SUBWOOFER
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?
Yes
INSTALL a new subwoofer speaker.

No
GO to D13 .
D13 CHECK FOR AN OPEN AND SHORT TO GROUND BETWEEN THE AFFECTED SUBWOOFER AND ITS RESPECTIVE AMPLIFIERS
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 Affected Subwoofer Speaker Pin Respective Amplifier Pin Circuit
1 4 176 (PK/LG)
3 3 179 (OR/RD)
2 4 189 (TN/LB)
4 3 187 (DB/OR)



Speaker Circuits—Left Side Affected Subwoofer Speaker Pin Respective Amplifier Pin Circuit
1 4 176 (PK/LG)
3 3 179 (OR/RD)
2 4 189 (TN/LB)
4 3 187 (DB/OR)


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?
Yes
INSTALL a new subwoofer amplifier.

No
REPAIR the circuit(s) in question. TEST the system for normal operation.

PINPOINT TEST E: NO SOUND FROM ALL OF THE SPEAKERS
Test Step Result / Action to Take
E1 CHECK FOR AUDIO UNIT OPERATION
Key in ON position.
Turn the audio unit on.
Does the audio unit display illuminate?
Yes
GO to E2 .

No
GO to Pinpoint Test A .
E2 CHECK THE SPEAKER OPERATION
Check the operation of all speakers.
Are all speakers inoperative?
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 .

PINPOINT TEST F: POOR QUALITY SOUND FROM ONE OR MORE SPEAKERS (NOT ALL SPEAKERS)
Test Step Result / Action to Take
F1 CHECK SOUND QUALITY
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?
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 .
F2 CHECK CIRCUITS BETWEEN AFFECTED SPEAKER(S) AND SUBWOOFER AMPLIFIERS
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 Affected Speaker Pin Subwoofer Amplifier Pin Circuit
RF 1 (convertible only) LH 7 822 (BK/LG)
RF 2 (convertible only) LH 8 287 (BK/WH)
LF 1 (convertible only) LH 7 822 (BK/LG)
LF 2 (convertible only) LH 8 287 (BK/WH)
RR 1 RH 7 822 (BK/LG)
RR 2 RH 8 287 (BK/WH)
LR 1 RH 7 822 (BK/LG)
LR 2 RH 8 287 (BK/WH)


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?
Yes
GO to F3 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
F3 CHECK CIRCUITS BETWEEN THE AUDIO UNIT AND THE SUBWOOFER AMPLIFIERS
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 Audio Unit C290a Pin Subwoofer Amplifier Pin Circuit
2 LH 5 167 (BN/OG)
6 RH 5 169 (LG/BK)
1 LH 6 168 (RD/BK)
5 RH 6 172 (LB/RD)


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?
Yes
GO to F6 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
F4 CHECK CIRCUITS BETWEEN AFFECTED SPEAKER(S) AND SUBWOOFER AMPLIFIER
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 Affected Speaker Pin Subwoofer Amplifier Pin Circuit
RR 1 7 822 (BK/LG)
RR 2 8 287 (BK/WH)
LR 1 7 822 (BK/LG)
LR 2 8 287 (BK/WH)


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?
Yes
GO to F5 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
F5 CHECK CIRCUITS BETWEEN THE AUDIO UNIT AND THE SUBWOOFER AMPLIFIER
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?
Yes
GO to F10 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
F6 CHECK FOR AN AUDIO SIGNAL TO THE SUBWOOFER AMPLIFIER HARNESS
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?
Yes
GO to F8 .

No
GO to F7 .
F7 CHECK AUDIO SIGNAL CIRCUITS AT THE AFFECTED SUBWOOFER AMPLIFIER FOR OPEN AND SHORT TO GROUND
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 Audio Unit C290a Pin Affected Subwoofer Amplifier Pin Circuit
2 8 172 (LB/RD)
8 7 169 (LG/BK)


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?
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.
F8 CHECK FOR AN AUDIO SIGNAL AT THE AFFECTED SUBWOOFER
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?
Yes
INSTALL a new subwoofer speaker

No
GO to F9
F9 CHECK FOR AN OPEN AND SHORT TO GROUND BETWEEN THE AFFECTED SUBWOOFER AND ITS RESPECTIVE AMPLIFIERS
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 Affected Subwoofer Speaker Pin Respective Amplifier Pin Circuit
1 4 176 (PK/LG)
3 3 179 (OR/RD)
2 4 189 (TN/LB)
4 3 187 (DB/OR)



Speaker Circuits—Left Side Affected Subwoofer Speaker Pin Respective Amplifier Pin Circuit
1 4 176 (PK/LG)
3 3 179 (OR/RD)
2 4 189 (TN/LB)
4 3 187 (DB/OR)


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?
Yes
INSTALL a new subwoofer amplifier.

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
F10 CHECK SPEAKER(S)
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?
Yes
INSTALL a new speaker. TEST the system for normal operation.

No
GO to F7 .
F11 CHECK THE AUDIO UNIT
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?
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.

PINPOINT TEST G: POOR QUALITY SOUND FROM ALL SPEAKERS
Test Step Result / Action to Take
G1 CHECK POOR SOUND QUALITY IN ALL SPEAKERS
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?
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 .

PINPOINT TEST H: THE SUBWOOFER IS INOPERATIVE
Test Step Result / Action to Take
H1 CHECK THE SUBWOOFER OPERATION
Key in ON position.
Turn on the audio unit and listen for correct subwoofer operation.
Are all subwoofers inoperative?
Yes
GO to H16 .

No
For convertible, GO to H2 .

For coupe, GO to H6 .

For Mach 1000 subwoofer speakers,GO to H10 .
H2 CHECK POWER TO THE SUBWOOFER AMPLIFIERS
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?
Yes
GO to H3 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
H3 CHECK GROUND TO THE SUBWOOFER AMPLIFIERS
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?
Yes
GO to H4 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
H4 CHECK THE SUBWOOFER AMPLIFIER ENABLE CIRCUIT FOR POWER
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?
Yes
GO to H5 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
H5 CHECK THE AUDIO UNIT
Substitute a known good audio unit.
Verify the operation of the audio unit.
Does the audio unit operate correctly?
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.
H6 CHECK THE VOLTAGE TO THE SUBWOOFER AMPLIFIER
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?
Yes
GO to H7 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
H7 CHECK THE GROUND TO THE SUBWOOFER AMPLIFIER
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?
Yes
GO to H8 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
H8 CHECK THE SUBWOOFER ENABLE CIRCUIT FOR POWER
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?
Yes
GO to H9 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
H9 CHECK CIRCUITS BETWEEN THE AUDIO UNIT AND THE SUBWOOFER AMPLIFIER
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?
Yes
GO to H10 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
H10 CHECK FOR POWER TO THE AFFECTED SUBWOOFER AMPLIFIER
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?
Yes
GO to H11 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
H11 CHECK FOR GROUND TO THE SUBWOOFER AMPLIFIER HARNESS
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?
Yes
GO to H12 .

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
H12 CHECK FOR AN AUDIO SIGNAL TO THE 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?
Yes
GO to H14 .

No
GO to H13 .
H13 CHECK AUDIO SIGNAL CIRCUITS AT THE AFFECTED SUBWOOFER AMPLIFIER FOR OPEN AND SHORT TO GROUND
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 Audio Unit C290a Pin Subwoofer Amplifier Harness Pin Circuit
2 8 172 (LB/RD)
8 7 169 (LG/BK)


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?
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.
H14 CHECK FOR AN AUDIO SIGNAL AT THE AFFECTED SUBWOOFER
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?
Yes
INSTALL a new subwoofer speaker.

No
GO to H15 .
H15 CHECK FOR AN OPEN AND SHORT TO GROUND BETWEEN THE AFFECTED SUBWOOFER AND ITS RESPECTIVE AMPLIFIERS
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 Affected Subwoofer Speaker Pin Respective Amplifier Pin Circuit
1 4 176 (PK/LG)
3 3 179 (OR/RD)
2 4 189 (TN/LB)
4 3 187 (DB/OR)



Speaker Circuits—Left Side Affected Subwoofer Speaker Pin Respective Amplifier Pin Circuit
1 4 176 (PK/LG)
3 3 179 (OR/RD)
2 4 189 (TN/LB)
4 3 187 (DB/OR)


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?
Yes
INSTALL a new subwoofer amplifier.

No
REPAIR the circuit(s) in question. TEST the system for normal operation.
H16 CHECK THE AUDIO UNIT
Substitute a known good audio unit.
Verify the operation of the audio unit.
Does the audio unit operate correctly?
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.

PINPOINT TEST I: LOUD POPPING WHEN CYCLING THE IGNITION SWITCH—CONVERTIBLE
Test Step Result / Action to Take
I1 CHECK SUBWOOFERS FOR LOUD POPS
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?
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.


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[CobraBob]

Wow! Great post. You pretty much covered everything. I mean, Ford did.

 

[hotcobra03]

guess work

yea it helps having fords disc,,i got tired of everyones guessing,,,it seams that when everyone has exhausted themselfs, they go to ford for answers,,so i start thier then come to forums for help.hope this does help him or someone else reading it

 

[frankin]

Hey sorry guys, I have been very busy with work and have not had time to post.
After I changed out the stock platinum plugs with a set of TR6, the ignition noise disappeared.
I did notice that the back passenger side plug hole had a lot of corrosion in it, like something had been leaking. It took me two hours to get that damn plug out! I sprayed this magic crap that a buddy gave me and the corrosion boiled away. I had to remove all the excess liquid from the corrosion cleaner. I used a syringe and a fish tank hose to draw the debris and fluid out. I had to also use a wet dry vac to make sure the plug hole was clear before I removed that plug.
When I pulled the coil over off the plug I had to clean rusty stains off of the boot and the coil. I believe this may have caused a high resistance in the circuit. I also had a miss at WOT before I changed these plugs. I would say that this plug was the culprit.
I have not found any leaks. I am going to check it again this weekend. This corrosion ruined the coating on the inside of the valve cover, I'm just glad it wasn't on the outside.
The stereo sounds good now, but I am thinking about the possibility of a bad head gasket.