Daytime Running Lamps (DRL) Inoperative

WARNING: This page is about a different car, the 2005 Buick LaCrosse and 2005 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

Step	Action	Yes	No
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Place the ignition in the ON position. Disengage the park brake. Expose the ambient light sensor to a bright incandescent lamp. Do the low beam headlamps illuminate at reduced intensity?	Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems	Go to Step 3
3	Install a scan tool. Expose the ambient light sensor to a bright incandescent lamp. With a scan tool, observe the Headlamp/DRL Output parameter in the body control module (BCM) data list. Does the scan tool display DRL?	Go to Step 4	Go to Step 5
4	Replace the headlamp module in the underhood fuse block. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems. Did you complete the repair?	Go to Step 6	-
5	Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement?	Go to Step 6	-
6	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 3