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).

NOTE: When installing a new SJB, it must be configured for this feature, if originally equipped. Refer to Module Configuration Special Tool(s) Used With Diagnostics.

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 (automatic transmission)
- Parking brake applied or released (manual transmission)

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.

The SJB can be configured to turn the DRL on for this vehicle. Refer to Module Configuration Special Tool(s) Used With Diagnostics for additional information on this programmable parameter.