Connecting to the Brake Light Wiring Circuit | HowStuffWorks This wire should lead to the brake light switch. The switch itself is connected with a plug, so you may need to splice your power wire to the power wire coming out of the plug. Once the switch has power, you need to connect the output wire from the switch to the rest of the brake light wiring harness.Author: Ed Grabianowski brake light switch wiring | eBay Brake Light Switch Wiring Harness Connector Housing 1953-1991 Chevy 60-91 GMC . Brand New. $9. Buy It Now. 4 Wire Connector of Brake Light Switch SLS407 Fits: Suzuki Forenza Reno Verona. Brand New. $10. 81 82 83 NOS MOPAR CHRYSLER DODGE CAR PLYMOUTH BRAKE LIGHT SWITCH WIRING 3747995 See more like this.