Ford 2003 Mustang Workshop Manual page 3451

Is the voltage greater than zero volts?
F4 CHECK CIRCUIT 13 (RD/BK) FOR SHORT TO POWER
Remove Fuse 4 (7.5A) and Fuse 10 (7.5A) from the
CJB.
Measure the voltage between multifunction switch
C202a Pin 507, Circuit 13 (RD/BK), harness side and
ground.
Is the voltage greater than 0 volts?
F5 CHECK CIRCUIT 1056 (DB, LG) FOR VOLTAGE
Disconnect: Headlamp C1041.
Measure the voltage between RH headlamp C1041 Pin
3, Circuit 1056 (DB/LG), harness side and ground.
Is the voltage greater than 0 volts?
Yes
REPAIR the circuit. TEST the
system for normal operation.
No
GO to F5 .
Yes
REPAIR Circuit 1056 (DB/LG).
TEST the system for normal
operations.
No
REPAIR Circuit 1055 (WH/LG).
TEST the system for normal
operations.