What is the working principle of a 4-wire brake switch?
1 Answers
A 4-wire brake switch essentially consists of two brake switches—one normally open and one normally closed. When the brake is pressed, the normally open switch closes, and the normally closed switch opens. Each of the four wires serves a different purpose: one is a 12-volt power supply, one is the brake signal wire for the ABS system ECU, one is the brake signal wire for the automatic transmission ECU, and one connects to the rear brake indicator light. 2-wire brake switch: A 2-wire brake switch operates on a break-and-make principle—when the brake is pressed, the switch closes; when the brake is not pressed, the switch remains open. 4-wire brake switch: The two wires on the side of the brake light switch control the brake lights, while the middle two wires provide the brake signal to the vehicle's computer (ECU). Based on this signal and other conditions, the ECU stops fuel supply to the engine, achieving fuel-saving effects.