No they don't flash on and off, I did not fully read what Mr Slug had to say so I had to go check this out on my truck. If you use the right turn signal the right head light turns off until the turn signal is turned off then the head light comes back on. To me this is a strange thing for the head light to turn off just because you use your turn signal.

 

May DC was thinking the DRL detracts from the blinker during the day?