When I pull the hand brake, the brake warning light turns on continuously (at the top of the oil temp/pressure gauge) and the flasher relay starts buzzing with a fairly high pitch. If I also have the left or right turn signal on at the same time, the brake warning light starts blinking like it’s supposed to.

It seems to me as if the brake warning light doesn’t pull enough current from the flasher relay to cause it to blink normally. What could be the cause of this?