The Nissan Path

High beams fine, daytime running lights are fine. Low beams not so good, one time the left will work but no right, the next time the right will work with a very faint left. Even when the operating low beam, either left or right, is working, light is not good and driving hazardous. Very periodically, both come on full brightness but, very periodically. Dealer let me swap out Daytime Running Light Relay to check mine, no change, so it isn't that relay. Any ideas of where to start???

Sounds like a bad headlight switch. If you're the mechanically capable and patient type, you might want to try taking apart the switch and cleaning the contacts and inspecting for any problems.