Ford 2003 Mustang Workshop Manual page 3405

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?
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
2
8
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
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.
Affected Subwoofer Amplifier
Pin
8
7
Yes
GO to F8 .
No
GO to F7 .
Yes
SEND the audio
unit to an
authorized Ford
audio system
repair facility.
TEST the system
for normal
operation.
Circuit
No
172
REPAIR the circuit
(LB/RD)
(s) in question.
169
TEST the system
(LG/BK)
for normal
operation.
Yes
INSTALL a new
subwoofer speaker
No
GO to F9