Buick LaCrosse daytime running lights remain on after shutdown causing battery drain on Buick LaCrosse

Some Buick LaCrosse owners report experiencing issues with daytime running lights that remain on after the vehicle is shut down, leading to battery drain. This problem may indicate a malfunction in the daytime running lamp module or relate to the body control module's (BCM) failure to check the voltage on the ambient light sensor correctly. Owners have noted that for the daytime running lights to function properly, specific conditions such as ignition position, parking brake status, and transmission gear need to be satisfied. A temporary workaround some have found effective is removing the headlight relay or the daytime running light relay from the fuse panel to see if the lights stay off overnight. If the HDM Beam Module removal successfully turns off the lights, it may signal the need for that module's replacement. Persistent issues could suggest a failure in the body control module, necessitating dealer intervention for repair.