Daytime Running Lamp: Description and Operation

DAYTIME RUNNING LAMPS (DRL)
With the daytime running lamps programmed 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 ambient light sensor indicates daytime conditions. The ambient light sensor is a light sensitive variable resistor that varies its resistance according to the level of (outside) ambient light. The IPM receives an input voltage proportional to the resistance of the ambient light sensor. 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 headlamp switch is in AUTO, the DIM either turns on the DRL or turns on the low beam headlights, after a 20 second delay depending on whether daylight or low light conditions are sensed. 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 to the left high beam. After the left high beam, the current flows through the HDHIBML fuse and through the HDHIBMR fuse. The current continues through the right high beam to ground G401. The high beam headlamps are now in series, which reduces the intensity. The DRL operate when the ignition switch is in the RUN position, and the parking brake is not set or the transmission is not in park. When these conditions have been met and the ambient light sensor indicates daytime conditions, the DRL will illuminate.

DAYTIME RUNNING LAMPS (NORWAY AND SWEDEN)
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 ambient light sensor indicates daytime conditions. Battery positive voltage is supplied from the rear fuse block EXPORT LGT fuse to the DRL relay coil and switch. When the dash integration module (DIM) determines that conditions are present to activate the DRL, the DIM grounds the DRL relay coil. This energizes the DRL relay coil. Battery positive voltage is supplied through the DRL relay switch and to each low beam headlamp. The low beam headlamps have ground at G401. The park lamps will also illuminate.