Daytime Running Lamps (DRL)

The daytime running lamps illuminate the low beam headlamps at a reduced intensity. With the daytime running lamps programed to be on, the DRL will operate when the ignition switch is in the ON position, the gear selector is out of the PARK position, the headlamp switch is in the OFF position, and the sunload sensor indicates daytime conditions. The sunload sensor is a light sensor combined with two photodiodes used to calculate the ambient light condition. The sunload sensor shall provide a variable output current source to the IPM to monitor external lighting conditions. When the IPM receives this signal, the IPM sends a class 2 message to the DIM and to the Rear Integration Module (RIM). When the twilight delay switch is moved out of the OFF position, the DIM either turns on the DRL or the low beam headlamps after a 20 second delay depending on whether daylight or low light conditions are sensed. For export Japan vehicles the DIM turns on the DRL or the low beam headlamps after a 3 second delay. Any function or condition that turns on the headlights will cancel the DRL operation. The DRL fuse in the underhood fuse block supplies battery positive voltage to the DRL relay switch. Battery positive voltage is also supplied to the DRL relay coil from the underhood fuse block which is energized by the DIM. When the DIM energizes the DRL relay coil, the current flows from the switch contacts of the DRL relay through the DRL resistor and to the left and right low beam headlamps.