9008 H13 Heavy Duty Headlight Wiring Harness with Relays Upgrade

The Aspire Auto Accessories 9008 H13 Heavy Duty Headlight Wiring Harness with Relays is a direct solution to the voltage drop problem built into most factory headlight systems. Stock wiring runs power from the battery through the headlight switch in the passenger compartment and back out to the engine bay — a long trip through wire that is typically 18 gauge or thinner. That distance and wire diameter starve your bulbs of voltage before they ever light up.

This harness reroutes that power delivery. When you flip the headlight switch, it triggers the relays on the harness, which then pull power directly from the battery through 14 gauge USA-made copper wire — standard with this kit. That shorter, thicker path means more voltage actually reaches the filaments, improving both low beam and high beam output. It also takes the heavy current load off the factory headlight switch, extending its service life.

We like the build quality here: machine-crimped connections with shrink wrap, split-loom wire protection, and high-temperature connectors rated to 572°F / 300°C with moisture seals. For buyers who want even more, Aspire offers upgrade paths — 12 gauge wiring, a 12 gauge fuse holder, soldered connections, and custom daytime running light circuits for low beam or high beam DRL configurations — each available as add-ons at checkout.

Available options:

• Select Harness & Power Wire Gauge: 14 Gauge Wiring & 14 Gauge Fuse Holder, 14 Gauge Wiring & 12 Gauge Fuse Holder (+$10), 12 Gauge Wiring & 12 Gauge Fuse Holder (+$30)
• Select Soldered Connections: No, Yes (+$10)
• Select Daytime Running Lights: No Daytime Running Lights, Low Beam Daytime Running Lights (+$30), High Beam Daytime Running Lights (+$30)