Ford 2003 Mustang Workshop Manual page 3402

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
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?
PINPOINT TEST E: NO SOUND FROM ALL OF THE SPEAKERS
Test Step
E1 CHECK FOR AUDIO UNIT
OPERATION
Key in ON position.
Turn the audio unit on.
Does the audio unit
display illuminate?
E2 CHECK THE SPEAKER
OPERATION
Check the operation of all
speakers.
Are all speakers
inoperative?
Respective Amplifier
Pin
4
3
4
3
Respective Amplifier
Pin
4
3
4
3
Result / Action to Take
Yes
GO to E2 .
No
GO to Pinpoint Test A .
Yes
REMOVE the audio unit and SEND it to an authorized Ford
audio system repair facility. TEST the system for normal
operation.
INSTALL a new
subwoofer
amplifier.
No
REPAIR the circuit
(s) in question.
TEST the system
Circuit
for normal
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)