SECTION 417-01: Exterior Lighting 2008 F-Super Duty 250-550 Workshop Manual
DIAGNOSIS AND TESTING Procedure revision date: 10/04/2007
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Daytime Running Lamps (DRL) Printable View (100 KB)
Special Tool(s) Vehicle Communication Module (VCM) and Integrated Diagnostic System (IDS) software with appropriate hardware, or equivalent scan tool
Principles of Operation
NOTE: The smart junction box (SJB) is also known as the generic electronic module (GEM).
NOTE: When installing a new SJB, it must be configured for this feature, if originally equipped. Refer to Section 418-01.
The SJB controls the DRL by using various inputs to determine whether or not the DRL should be illuminated. These inputs include:
Ignition switch position
Headlamp switch position
Headlamps on or off
Transmission gear selection (automatic transmission)
Parking brake applied or released (manual transmission)
When the DRL is active, the SJB provides a pulse-width modulated (PWM) voltage to the low beam headlamps. This illuminates the headlamps at a reduced intensity.