Benny,

A volt/ohm meter will help you diagnose all sorts of electrical problems,
and is a good investment for under $40 at Radio Shack.

I have never heard of the stop light switch in a Toyota failing, so I doubt
if the switch in yours is bad.  The switch is mounted above the brake pedal,
and with a volt/ohm meter, you can check it for continuity when the pedal is
depressed.  Most places will not allow you to return electrical parts, but
hopefully, you will be able to if it is still in the original packaging and
has not been installed.

If the tail lights work but the brake lights do not, then the first thing to
check are the bulbs.  Are the left, right, and center high mounted stop lamp
all not working?  If any one out of the three brake lights is working, then
the brake light switch is good.  With the meter, check for voltage at the
bulb sockets.  If you get 12 volts at the socket when the brake light is
depressed and the negative lead for the meter on a ground like the trunk
latch, then the ground for the lights is loose or disconnected.  You  can
look for the ground point and check it or just run a new ground wire.  Also
look for corrosion in the bulb sockets and cuts in the wire where it passes
from the trunk lid to the body.

The mutli-function switch is NOT the problem.  The switch that eliminates
the stop lights is mounted above the brake pedal. I would check for proper
adjustment and continuity before replacing it however.

mike