They're white lights. The mnemonic is "You go blank on a test" meaning you forget everything. What happens is you are sending a fake turning signal from the wheel set you test (inboard or outboard) to the anti-skid box. The box then releases pressure from the other set of wheels so that they too can turn. You would not want to see these lights on in normal ops.
Most air carriers removed the nose brakes as they (1) only came on when the brake pedals were depressed more than 50% (2) weighted a couple hundred pounds which is a passenger if you're weight limited. I've seen a few VIP planes that still had them because their CG was messed up with all the stuff in back and they needed ballast up front.