Someone already suggested... If your DRLs are still activated (ie. not disabled on purpose), they should come on when the ECU gets the signal that the EEEEEEEEE-(LOL, got to love that)brake switch is in the fully release position. So park your car right up against a wall (front of car to the wall...) and let us know if the DRLs come on when you release the hand brake. If they do not, it is likely the switch. If they do, the switch is functioning and the source of your alarm is elsewhere.
Mine had a flakey alarm...the ABS light and Brake light (I myself don't have the much covetted EEEEEEEEEEE-brake light...) would flash momentarily (until I caught the moment it was just random mystery beeping...). Showed circuit 30 voltage inplausible. Of the many theories floated, the fault cleared up after I discovered that my battery leads were loose. Tightening these also fixed my CD ejecting whenever I would start the car w/ a CD playing in the player... At the time I tightened the leads I also checked the grounds under the battery. I found NO corrosion, but removed and reassembled with silicone grease as a protectant. I think the origin of both faults was the poor connection to the battery. Mine would happen at random times and frequencies. Would usually only beep 3x...not continuously.
On my list of to-do's, had the fault not conveniently disappeared, were: 1. Check wheel speed sensors rings for corrosion/buildup, 2. check wheel speed sensors for dirt/grime build up. and 3. flush the brake fluid. Hopefully the Daytime Running Light check will give you a direction in which to go.