Brake Light Wiring Diagram | HowStuffWorks Brake Light Wiring Diagram - This brake light wiring diagram gives you a clear picture of where each wire goes. Visit HowStuffWorks to check out this brake light wiring diagram.Author: Ed Grabianowski Chevy Silverado Brake Light Troubleshooting | It Still Runs Check the Brake Lights Circuit. Then check the brake light switch on the bake pedal arm. Back probe the switch terminals with a test light. Only one of the switch terminals should turn on the test light. When you depress the brake pedal, both switch terminals should turn on the test light. If only one of the wires turns on the test light,..