Yes , with a volt meter . Find the switch an back probe wires ,testing for voltage in , then press the brake pedal an check for voltage on wire going out . You'll need a wiring diagram so you know which wire is the right one's . You can find free wiring diagrams at http://bbbind.com/free_tsb.html enter vehicle info . year make model an engine size .Under system click on lighting ,then under subsystem click on stop lamp . none of the brake lights work including the high mount stop lights ? A electronic module (smart junction box) controls the lower brake lights . The high mount are controlled directly from brake light switch .