Headlight socket wiring 9003/H4 - Maintenance/Repairs The 9003/H4’s wiring arrangement is like this: the middle connection is the positive wire and there are two connections on either side that that are grounds. The grounds determine which way the electricity will flow. Mess the sides up when you are wiring up the connections, and Installation Guide for HID & LED Headlights | XenonHIDs XenonHIDs is your #1 source for LED Headlights and Xenon HID Kits with 46500+ reviews from happy customers. Lifetime Warranty and Free Shipping. How to Re-Pin H4 (aka 9003) HID Bulb (also apply for Aug 27, 2013This is a video showing you How to re-pin an 9003/H4 single beam HID bulb. This installation also applies for Bixenon H4, H13 and 9007. Brought to you by htt.. Related searches for h4 bulb wiring diagram h4 headlight wiring diagramh4 headlight wiringh4 plug diagram9003 bulb wiringh4 headlight plug pin outh4 headlight plugh6054 wiring diagramh4 headlight plug connectors