Is it illegal to flash high beams in NY State to warn of speed trap or signal a drive that they can pull out of a parking lot ?

Vehicle and Traffic Law Section 375 (3) says that, "whenever a vehicle approaching from ahead is within [500] feet " your headlights "shall be operated so that dazzling light does not interfere with the driver of the approaching vehicle." In 2009, an appellate court held that "the mere flashing of lights, alone, does not constitute a violation of the statute." You can read the case here: https://scholar.google.com/scholar_case?case=10193957285354863056

I suggest you review the case at:

http://decisions.courts.state.ny.us/ad3/Decisions/2017/524369.pdf

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You have an arguable defense but it would be recommended to have an attorney to assist you, contact a traffic lawyer in your area.

No, as explained by counsel from your state. Get a defense lawyer and win your case!

In 2009, the New York Supreme Court Appellate Division (Fourth Department) held that the flashing of lights alone is not a violation of New York Vehicle and Traffic Law Section 375 [3], that stopping a vehicle based upon that is illegal, and all evidence gathered as a result of the illegal stop should be suppressed.