Ford 2003 Mustang Workshop Manual page 3540

Circuit 1205 (BK); and between DLC C251 Pin 10,
Circuit 915 (PK/LB), harness side and C251 Pin 16,
Circuit 1047 (LG/RD), harness side.
Is the voltage zero volts for any measurement?
G7 CHECK CIRCUIT 914 (TN/OG) AND CIRCUIT 915
(PK/LB) FOR OPEN — PCM C175 DISCONNECTED
Disconnect: PCM C175.
Measure the resistance between PCM C175 Pin 16,
Circuit 914 (TN/OG), harness side and DLC C251 Pin
2, Circuit 914 (TN/OG), harness side.
Measure the resistance between PCM C175 Pin 15,
Circuit 915 (PK/LB), harness side and DLC C251 Pin
10, Circuit 915 (PK/LB), harness side.
Are the resistances less than 5 ohms?
G8 CHECK CIRCUIT 914 (TN/OG) AND CIRCUIT 915
(PK/LB) FOR THE SOURCE OF THE CONCERN — PCM
C175 DISCONNECTED
Key in OFF position.
Disconnect: PCM C175.
Key in ON position.
Measure the voltage between DLC C251 Pin 2, Circuit
914 (TN/OG), harness side and C251 Pin 4, Circuit
1205 (BK); and between DLC C251 Pin 2, Circuit 914
(TN/OG), harness side and C251 Pin 16, Circuit 1047
(LG/RD), harness side.
Yes
GO to G8 .
No
REPAIR the circuit(s) in question
between in-line C215 and DLC
C251. For additional information,
REFER to Communication
Circuit Wiring Repair . TEST the
system for normal operation.
Yes
GO to G9 .
No
REFER to the Powertrain
Control/Emissions Diagnosis
(PC/ED) manual Section 3 for
diagnosis and testing.