Daytime Running Lamp: Description and Operation

DAYTIME RUNNING LAMPS (DRL) - DOMESTIC/CANADIAN
The daytime running lamps (DRL) consist of the front turn signal lamps illuminated continuously. The DRLs will operate when the following conditions are met:
- The ignition is in the RUN or CRANK position.
- The shift lever is out of the PARK position.
- The high and low beam headlamps are OFF.
- The park brake is not applied.

When conditions for DRL operation exist, the powertrain control module (PCM) sends a message via GMLAN serial data to the instrument panel module (IPM) indicating the transmission has been removed from the PARK position. The ambient light sensor is a light sensitive transistor that varies its voltage signal to the HVAC control module in response to changes to the outside (ambient) light level. When the HVAC control module receives this signal, it communicates via GMLAN with the IPM. The IPM either turns on the DRLs using a reduced output or the low beam headlamps at full intensity for auto headlamp operation. Any function or condition that turns the headlamps ON will cancel the DRLs operation.

DAYTIME RUNNING LAMPS (DRL) - NORWAY/SWEDEN
The daytime running lamps (DRL) consist of the right and left low beam headlamps illuminated continuously and the park lamps. The DRLs will operate when the following conditions are met:
- The ignition is in the RUN or CRANK position.
- The shift lever is out of the PARK position.
- The high and low beam headlamps are OFF.
- The park lamps are OFF.
- The fog lamps are OFF.
- The park brake is not applied.

When conditions for DRL operation exist, the powertrain control module (PCM) sends a message via GMLAN serial data to the instrument panel module (IPM) indicating the transmission has been removed from the PARK position. The ambient light sensor is a light sensitive transistor that varies its voltage signal to the HVAC control module in response to changes to the outside (ambient) light level. When the HVAC control module receives this signal it communicates via GMLAN with the IPM. The IPM either turns ON the DRLs using a reduced output or the low beam headlamps at full intensity for auto headlamp operation. Any function or condition that turns the headlamps ON will cancel the DRLs operation. The DRLs consists of the low beam headlamps. With the headlamp switch in the OFF position, the headlamps will either be turned ON or OFF, after an approximate 8 second delay depending on whether daylight or low light conditions are sensed.