Brake light switch is installed in the top position of the brake pedal , contact contact when the pedal is depressed, the brake light switch control the brake light relay, the relay provides voltage to the brake lamp lighting system, lighting system used in parallel to bulb lit. Simple quality judgments: Using the the multimeter measuring the plug connection piece of brake light switch , direct table action, if the instructions do not move the table should be replaced. Or gently press the table without putting direct response should also be replaced. When installing, mustbe according to the product requirements strictly.