How do you turn on the retractable headlamp washer in a bmw 328xi? ?

I looked in the owner's manual, it didn't say. How do you turn on the retractable headlamp washer in a bmw 328xi? ?it squirts when you trigger the washer to spray your windshield more than once, or if you hold it on for longer than a couple of seconds. the first time it "went off" on me, i didn't know what had happened, because i wasn't trying to clean the headlights, just the windshield! i had figured there was another lever of button to wash the headlights.How do you turn on the retractable headlamp washer in a bmw 328xi? ?They only work when the headlights are turned on and you use the screen washer. Make sure your washer bottle is topped up because the headlamp washer motor is higher up the washer bottle than the screen washer and so will run out of water sooner. Once the level drops too low it takes ages to "bleed" back through.