Principles of Operation

Daytime Running Lamps (DRL)

Principles of Operation

NOTE: The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).

The SJB controls the Daytime Running Lamps (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
- Parking brake input status

The SJB can be configured to turn the DRL on for this vehicle. Refer to Information Bus for additional information on this programmable parameter.

Vehicles With Halogen Headlamps

When the DRL is active, the SJB provides a pulse-width modulated voltage to the low beam headlamps. This illuminates the headlamps at a reduced intensity.

Vehicles With High Intensity Discharge (HID) Headlamps

When the DRL is active, the SJB energizes the fog lamp relay. This illuminates the fog lamps at full intensity.