Vtec sub harness kit for haltech 550/750. This rely kit is needed in order to run vtec, the only wire that needs to be hooked up on your end is a 12v source. We usually go directly to the fuse box and can help you with this if needed. Once you order, if you're looking for help email us RCautoworks@gmail.com with the year/make/model and we will pull a schematic up for your car and send with your order. This harness also comes with an inline fuse as well.