Review on High-Performance 1 Pack 40/30 AMP 12 V DC Waterproof Relay and Harness - Heavy Duty 12 AWG Tinned Copper Wires, 5-PIN SPDT Bosch Style Automotive Relay by Ashutosh Takumatla

Bought to connect truck horns and selected for the 12 gauge wire and waterproof relay. Since the relay plugs into the wire harness and the relay pin markings are hidden, I suggest that you label the wire harness colored wires with the relay pin numbers to help with proper wiring. I recommend using the red wire as battery power through the fuse to play pin 30, pin 85 as ground, and pin 86 or 87 as the trip wire from the switch. Download circuit diagrams from the Internet.