What are the four wires of the brake switch?
2 Answers
The four wires of the brake light switch are: one is the 12-volt power supply, one is the brake signal wire to the ABS system ECU (ECU stands for Electronic Control Unit, also known as the vehicle's onboard computer), one is the brake signal wire to the automatic transmission ECU, and one goes to the rear brake indicator light. Below is some relevant information about the brake light: 1. Rear brake light: The rear brake light is controlled by the vehicle's lighting system. The brake switch does not directly control the rear brake light; instead, the brake switch signal first goes to the vehicle's lighting control system, which then controls the brake light. 2. Function: The brake light is highly bright and noticeable, primarily used to alert following vehicles that the car is slowing down or stopping. Incorrect use or malfunction of the brake light can easily lead to rear-end collision accidents.
The four wires at the brake switch are actually clearly divided. One pair is specifically for the brake lights: one input wire receives power from the fuse, and the other output wire goes to illuminate the rear brake lights. The moment you press the brake pedal, these two paths connect, and the light immediately turns on to signal the vehicle behind. The other pair of wires is mainly for cruise control: one point is normally closed to keep the cruise system operational; the other end disconnects when the brake is pressed, instantly stopping the cruise function to prevent the car from moving uncontrollably. This design is quite clever, managing two functions with one action. If you notice the brake lights flickering or the cruise control stopping unexpectedly during normal driving, remember to check that the wires at the switch aren’t loose or corroded. Otherwise, small issues can lead to big hazards. Repairs are simple, but don’t disassemble it recklessly—watch some tutorial videos before attempting any work. If the wires are aged, replace them with original parts; safety is the top priority.
