Front part of brake fluid reservoir was out, so I filled it. I started the vehicle and the red brake light on the dash came on. It wasn't on before, and the brake pedal now goes almost to the floor. I pumped the pedal the brakes worked fine before. I heard a whining noise in engine compartment. I thought it was coming from the distributor, as it has made a whining noise in the past and then stopped. That's when I spotted the low brake fluid in the front section only.