FIX DIM HEADLIGHTS & IMPROVE LIGHT OUTPUT: Upgrade your old factory headlight wiring with this H4 LED headlight relay harness kit. Fix common issues including dim headlights, flickering headlights, voltage drop, weak high beam/low beam performance and insufficient power supply. This fused relay wiring harness delivers stable battery power directly to your H6054 LED headlights, improving brightness and reliability during night driving. UPGRADE MADE SIMPLE: As Toyota Pickup and Toyota Tocoma use a double ground which leads to the headlights not work or only one beam work, this h4 Harness is a must to fix the problem.Ditch the hassle and save some serious cash by using this h4 wiring harness to flip your headlight system from ground-switched (2 toggled grounds + 1 constant hot) to positive-switched (2 toggled hots + 1 constant ground). Easy peasy! FIX DIM HEADLIGHT ISSUES: This 1set 2-headlights h4 headlight relay harness Fixes cars with 2 pcs H4 plug headlamps, such as 7x6 5x7 headlights. Problems like Dim Headlights, Flickering Headlights, Back Feeding Power, Malfunctioning Headlights when using Hi/Low Beams can be fixed with this kaslight 2-headlight h4 headlamp relay. Make a big improvement for visibility on your cars at night. IMPORTANT NOTICE: If your socket pin is not standard, KASLIGHT H4 9003 HB2 Wiring Harness is needed, as To-yota Pickup and To-yota Tocoma use a double ground which leads to the headlights not work or only one beam work, this Harness is a must to fix the problem. ALSO FIXES: Overloading the Headlight Switch, Overheating Plugs. If you are upgrading to LED Bulbs or are having trouble with your 7"x6"headlight, 4x6"led headlight, 5-3/4" or any other H4 plug headlights not working properly, plug-n-play conversion harness, this is your fix!! Package includes one set h4 socket led headlight relay kit.