I've checked my 1993 Sonata manual (U.S.)  It doesn't show a brake lamp
warning lamp.  It shows the fuse in question as fuse #3 in the dash fuse
box.  Check the kick panel under the left side of the dash for the fuse
box.  Also be sure to check the bulbs and the brake light switch on the
brake pedal.  

Okay, I take that back.  It appears the DRL unit has the ability to
illuminate the BRAKE warning lamp using the same circuit as the parking
brake and fluid level sensor in the master cylinder.

My manual does have a DRL schematic (for Canadian vehicles).  Here's what
I can figure:

pin 1 -- red -- applies ground to illuminate brake warning lamp, receives
ground from parking brake lever switch.

pin 2 -- white/black -- privides ground to headlamp relay, energizing
headlamps.

pin 3 -- unused

pin 4 -- red/white -- receives power from fuse 11 in dash fuse box

pin 5 -- yellow/red -- receives ground from light switch when in "park" or
"head" position.

pin 6 -- yellow/green -- provides ground to tail lamp relay, operating
tail lamps.

pin 7 -- black -- DRL unit ground

pin 8 -- white/green -- provides ground when alternator is not charging
(tells DRL unit whether car is running).

pin 9 -- brown -- DRL unit grounds this wire, causing either dim headlamps
(low and high beams in series) or low beams, depending on status of head
lamp relay.