The daytime running lamp (DRL) system in a GMC Sonoma is controlled by the body control module (BCM). The BCM energizes the DRL relay in order to illuminate the low-beam headlamps when the engine is running. The low-beam headlamps illuminate at approximately 50 percent of their normal brightness level. The DRL system makes the vehicle more visible to other motorists during daylight hours, preventing auto accidents and other types of visibility-related collisions.
Turn off the ignition and place the truck in park or first gear (manual transmission). Set the parking brake and open the hood.
Open the under hood fuse box. This is located on the right side of the engine compartment, between the air filter box and the right side strut tower.
Look on the inside of the fuse box cover. Read the diagram to determine the location of the DRL relay inside the fuse box.
Remove the DRL relay. Close the cover on the fuse box.
Start the engine. Check to make sure that the headlamps are not powered on.
