Line position function: (button + 12V line)Black line (key LED light negative control)Yellow line (positive trigger output control of key switch)3-wire function + Positive trigger output control. After pressing the start button, the yellow wire outputs + 12V ; the black wire is connected to the key lamp to control the negative output wire, and the key lamp lights.Product Specification:Type Car Engine Start Stop ButtonFitment Only for DC 12V modelscolour:blackMaterial ABSsize:53.8mm*10mmPackage Contents:1x Engine Start Stop ButtonOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.