Ford 2003 Mustang Workshop Manual page 3406

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
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
1
3
2
4
Speaker Circuits—Left Side
Affected Subwoofer
Speaker Pin
1
3
2
4
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)
Key in OFF position.
Substitute the affected speaker with a known good component.
Key in ON position.
Respective Amplifier
Pin
4
3
4
3
Respective Amplifier
Pin
4
3
4
3
Yes
INSTALL a new
subwoofer
amplifier.
No
REPAIR the circuit
(s) in question.
TEST the system
for normal
Circuit
operation.
176
(PK/LG)
179
(OR/RD)
189
(TN/LB)
187
(DB/OR)
Circuit
176
(PK/LG)
179
(OR/RD)
189
(TN/LB)
187
(DB/OR)
Yes
INSTALL a new
speaker. TEST the