Ford 2003 Mustang Workshop Manual page 3257

PINPOINT TEST E: A SINGLE ILLUMINATION SOURCE IS
INOPERATIVE
E1 CHECK VOLTAGE TO THE SINGLE
ILLUMINATION SOURCE
Disconnect: Inoperative Illumination Source.
Place the headlamp switch in the ON position.
Rotate the instrument panel dimmer switch to the
full illumination position.
Measure the voltage between the inoperative
illumination source, circuit 19 (LB/RD), harness
side and ground.
Is the voltage greater than 10 volts?
E2 CHECK SINGLE ILLUMINATION SOURCE
GROUND
Measure the resistance between inoperative
illumination source, circuit 1205 (BK), harness side
and ground.
Is the resistance less than 5 ohms?
Test Step Result / Action to Take
Yes
GO to E2 .
No
REPAIR the circuit. TEST the system
for normal operation.
Yes
INSTALL a new component in
question. TEST the system for normal
operation.
No
REPAIR the circuit. TEST the system
for normal operation.