Ford 2003 Mustang Workshop Manual page 3513

SECTION 417-04: Daytime Running Lamps
DIAGNOSIS AND TESTING
Daytime Running Lamps (DRL)
Refer to Wiring Diagrams Cell
Special Tool(s)
73III Automotive Meter or
equivalent
105-R0057
Principles of Operation
Daytime Running Lamps (DRL)
The daytime running lamps (DRL) system operates the low beam headlamps at a reduced intensity.
The DRL module (15A270) supplies pulse width modulated (PWM) voltage, approximately 75%-92%
of battery voltage, to the low beam headlamps when the following conditions are met:
The parking brake control is released.
The high beam headlamps are disabled.
The ignition switch (11572) is in the RUN position.
The DRL module remains enabled when the low beam headlamps are turned on.
Inspection and Verification
1. Verify the customer concern by operating the system.
2. Visually inspect for obvious signs of mechanical and electrical damage.
Visual Inspection Chart
Mechanical
Damaged DRL module
Damaged parking brake signal switch and
bracket (15A851)
3. Verify the headlamps are operating correctly. Correct any concerns before proceeding to the
97 , Daytime Running Lamps for schematic and connector information.
2003 Mustang Workshop Manual
Electrical
Blown battery junction box (BJB) Maxi-
Fuse FOG+DRL (20A)
Damaged wiring harness
Loose or corroded connection
Damaged DRL module
Damaged parking brake signal switch and
bracket