The Relay and Harness are the add on feature to our wired tracking devices. (GT1900 & GT1510). The Relay enables the users to kill a remote process that is 12v. This is great for aftermarket ECUs, or SxS, ATV, Seadoo, Pontoon boats. 

The Relay and Harness will have 3 wires coming out of it. Red, Blue and Green.
When wiring in the relay, you'll find the 12v process you want to enable or disable. You'll cut that wire in half, and connect the 12v wired side to the Blue wire of the IO harness. Then the Red line of the IO Harness will connect to the other side of the cut wire. The Green wire on the IO Harness will connect to the green wire on the tracking device.