Daytime Running Lamp: Description and Operation

The Daytime Running Lamp (DRL) system consists of a DRL Module and an Ambient Light Sensor. During daylight hours, the DRL Module turns "ON" the Front Turn Signal Lights if:
1) Ignition is "ON"
2) The Headlights are "OFF" and
3) If the Park Brake is "OFF."
As darkness approaches, the DRL Module will turn "OFF" the Front Turn Signal Lights and turn "ON" the Park Lights and Headlights.

The DRL Module determines daylight or nighttime hours by receiving voltage from the Ambient Light Sensor. As darkness approaches the Ambient Light Sensor will change resistance and thus change the voltage received by the DRL Module. The Control Logic within the DRL Module receives its voltage from the TURN B-U Fuse 2 and the GAGES Fuse 9. The GAGES Fuse also supplies voltage to the relays within the DRL Module and supplies voltage to the Front Turn Signal bulbs during DRL operation through the Left and Right DRL Relays within the DRL Module. The Headlamp Switch supplies voltage for the Headlamps, through the Headlamp Relay contacts within the DRL Module, during nighttime hours. The TAIL LTS Fuse supplies voltage to the Park Lights during nighttime hours. During DRL operation, the Turn Signals and Hazard Flasher will operate normally. The Park Lamps and/or the Headlamps may be operated manually at any time by using the Headlamp Switch.

The DRL Module will not operate if the system voltage is less than 9 volts or greater than 18 volts. When the Park Lamps/Headlamps are turned "OFF," and the Ambient Light Sensor indicates a night condition, the Park Lamps will illuminate when the Ignition Switch is moved to the "CRANK" position.