Headlamps fluttter on and off

I've been experiencing the headlamps fluttering on and off, even when the car is sitting still (so much for shorting out?). Both lights switch at the same time, and no amount of wire wiggling seems to cause the problem.

Is there a relay or switch that I should try replacing?

Winter is coming and driving during the "day" is about to become more difficult.

Testing with a voltmeter would be the best way. Start at the headlight switch and work your way along the wire until you fine the loose connection. Might even be in the switch.