Heavy Duty Relay Harness

Dapper Lighting Heavy-Duty H4 Relay Harness – DLRH4-HD and DLRH2-HD

If your headlights are underpowered or dim, chances are your classic car's original wiring can’t keep up. The Dapper Lighting Heavy-Duty H4 Relay Harness fixes that by bypassing the factory wiring and delivering full power directly from the battery—restoring voltage, improving brightness, and protecting your electrical system.

This upgraded version features:

• 12 AWG main power and ground leads

• 14 AWG headlamp outputs

• Ceramic H4 plugs for heat resistance

• Waterproof 30A Bosch-style 4-pin relays

• Heavy-duty waterproof inline fuse

Compatible with 2-headlight or 4-headlight systems. In 4-headlight setups, all four lamps receive power during high beam operation.

Why use a relay kit?
Your stock wiring often suffers voltage drop from age, corrosion, or poor factory design. A relay kit routes power directly from the battery, significantly improving headlight brightness—especially noticeable in halogen systems.

Who should use this kit?
Anyone running stock or upgraded halogen bulbs, or LED conversions in classic vehicles. It’s especially useful if your headlights flicker, dim under load, or just don’t light up the road like they should.

Covered by Dapper Lighting’s 5-Year Worry-Free Warranty. Need help or a replacement? Just reach out—we’ve got your back.