Ranger 2WD V6-3.0L (2008)
Daytime Running Lamp: Initial Inspection and Diagnostic Overview
PRINCIPLES OF OPERATION
NOTE: The smart junction box (SJB) is also known as the generic electronic module (GEM).
The DRL are controlled by the smart junction box (SJB). The SJB operates the low beam headlamps at a reduced intensity. The DRL driver (integral to
the SJB) supplies pulse-width modulated (PWM) voltage to the low beam headlamps when the following conditions are met:
-
The high beam headlamps are not on
-
The ignition switch is in the RUN position
-
The parking brake is not engaged
The SJB utilizes a protective circuit strategy for many of its outputs (for example, the headlamp output circuit). Output loads (current level) are
monitored for excessive current (typically short circuits) and are shut down (turns off the voltage or ground provided by the module) when a fault is
detected. A continuous DTC is stored at that time of the fault. The circuit then resets after an ignition cycle or customer demand of the function
(switching the component on, battery saver being energized).
When an excessive circuit load occurs several times, the module shuts down the output until a service procedure is carried out. At the same time, the
continuous DTC that was stored on the first failure cannot be cleared by a command to clear the continuous DTCs. The module does not allow this code
to be cleared or the circuit restored to normal until a successful on-demand self-test proves that the fault has been repaired. After the on-demand self-test
has successfully completed (no on-demand DTCs present), the continuous DTC clears and the circuit function returns.
