Principles of Operation

WARNING: This page is about a different car, the 2009 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: The smart junction box (SJB) is also known as the generic electronic module (GEM).

NOTE: The DRL is not a programmable parameter for this vehicle.

The Smart Junction Box (SJB) controls the DRL by using various inputs to determine whether or not the DRL should be illuminated. These inputs include:

Ignition switch position
Parking brake switch input
Headlamps on or off
Transaxle gear selection

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.