If you can, find another headlamp and unplug your offside/drivers headlamp and plug the wiring into the "spare" unit. If the fault persists, it's not the headlamp, if the DRL comes up bright on the spare unit then it's the light unit.
However, you may find if the spare is bright, the original might "miraculously" become bright - this points to corroded/dirty connections within the plugs.