The brake lights on my 1999 RX300 have stopped working. Is there an activator switch that is easy to replace? I saw a plunger style switch on the brake pedal. Is this the culprit?

 

Welcome to CL, ftitarpon!

Is the brake light at the top of the window functioning? That switch is probably the brake light switch (I've forgotten what it looked like on my 300), although it could be connected to the cruise control. Use a test light (12V bulb with a couple of probes) to check to be sure

1. It's the switch.
   
   
2. It's faulty.

If the switch seems to be ok, check at one of the lamp assemblies in the rear. It's almost impossible to have both lights burn out at the same time, but there could be a broken connection that would affect all three.