Connect your H4 9003 HB2 headlight bulbs to FULL BATTERY VOLTAGE for MAXIMUM BRIGHTNESS with the Aspire H4 9003 HB2 Upgraded Heavy Duty Headlight Wiring Harness with Relays! At Aspire Auto Accessories, we manufacture and carry our own Heavy Duty Wiring Harnesses with Relays that fit a wide selection of bulbs commonly found in most vehicles. 

This H4 9003 HB2 Heavy Duty Headlight Wiring Harness with Relays Upgrade is one of the most simple and effective ways to improve dim headlights and overall headlight performance by increasing both your low beam and high beam illumination. Perfect for dark roads, off-road, and rural areas! 

 Features

• This kit is designed to fit vehicles equipped with H4 9003 HB2 bulbs
• Gives you brighter low beam and high beam 
• All connections are machine crimped and shrink wrapped to the highest industrial standards.
• Harness is covered with premium split-loom covering to protect wires
• High Temperature Connectors - Max Temperature = 572º F / 300º C

Select Wiring Harness Gauge &  Power Wire Gauge

• 14 Gauge - Our standard wire gauge
• 12 Gauge Wiring - Upgrade your headlight wire that goes to the harnesses relays and your vehicle's headlights to thicker wire.
• 12 Gauge Fuse Holder - Upgrade your power wire that goes to the harnesses relays and your vehicle's battery to thicker wire.

Soldered Connections

• Have us solder your machine crimped connections so you can have the most secure & reliable harness. Solder is NOT common in vehicles, but is routine in aircraft because it produces the best union of wire to terminal.

Select Daytime Running Lights 

• No Daytime Running Lights - Select this option if you disabled your daytime running lights or if your vehicle does not have low beam or high beam daytime running lights
  
• Low Beam Daytime Running Lights - Select this option if your vehicles uses the low beam for daytime running lights and we will add a custom made circuit to allow the harness to function properly.
• High Beam Daytime Running Lights - Select this option if your vehicle uses the high beam for daytime running lights  and we will add a custom made circuit to allow the harness to function properly.

Reason #1: To minimize the VOLTAGE DROP in factory headlight systems. Voltage drop lowers the energy delivered to your headlight filaments which reduces their output. Voltage drop is a result of electrical power being run for long distances through thin wires. You can visualize voltage drop by imagining yourself drinking a beverage through a long thin straw (electric energy is the "beverage" and the wire is the "straw"). 

Reason #2: Using a H4 9003 HB2 Heavy Duty Relay and Wiring Harness Upgrade reduces the current that is handled by the head light switch by a large margin. This reduction in current greatly increases the life of your head light switch.

For example: Your factory headlight systems POWER flows from BATTERY to HEAD LIGHT SWITCH in passenger compartment. When head light switch is turned on, POWER flows back out into engine compartment and then illuminates HEAD LIGHTS. Notice the long distance that power must travel. To make matters worse, typical factory headlight wires are 18 Gauge or LESS. These long runs of thin wires starve your head lights of energy.

ADDING A H4 9003 HB2 HEADLIGHT WIRING HARNESS UPGRADE WITH RELAYS 

Increases the power delivered to your head lights by minimizing the distance power must flow from battery to head lights AND by passing this power through thick, 14 Gauge or 12 Gauge USA made wire (Smaller Gauge = THICKER wire) with the highest quality copper conductor. 

AFTER INSTALLING A H4 9003 HB2 HEADLIGHT WIRING HARNESS UPGRADE WITH RELAYS 

POWER flows from BATTERY to HEAD LIGHT SWITCH in passenger compartment. When head light switch is turned on, POWER flows back out into engine compartment and then ACTIVATES RELAYS on the wiring harness. The RELAYS then CONNECT the HEAD LIGHTS DIRECTLY to BATTERY through 14 Gauge or 12 Gauge wires.

In simplified terms, the H4 9003 HB2 Heavy Duty Headlight Wiring Harness with Relays Upgrade is triggered by the head light switch and when triggered, the harness supplies power to the head lights through a more efficient path.

Can't find a harness that fit's your vehicle's bulbs or unsure about product fitment? If you have any questions, please let us know and we'll be happy to help!