Amazon: h4 headlight harness H4 Wiring Harness Headlight Socket Heavy Duty 14AWG Ceramic Headlight Plug For Car Truck Boat Marine Headlight Fog Light Retrofit - H4/9003(Pack of 2) 4.1 out of 5 stars 13. $7 $ 7. 68. Get it as soon as Tue, Mar 26. FREE Shipping on orders over $25 shipped by Amazon. H4 Upgraded Headlight Harness - ksuspensionfab H4 Wiring Harness Upgrade for any vehicle with the H4 light plug Increase your OEM lighting output by a minimum of 50% (usually more)Save your light switch from burning up like they always doTake the load off the system and wire your lights directly to the battery!Plug 'n Play designNo wiring needed Watch our video below for some guidance on how the install will go!