HD Relay: H9

Power your HID lighting system the right way with the Morimoto HD Relay Harness H40. Designed to deliver clean, stable battery voltage directly to your HID ballasts, this premium relay harness eliminates the voltage drops that can cause flickering, inconsistent startup, and unreliable headlight performance.

Unlike factory headlight circuits—which are designed to power standard halogen bulbs—the H40 provides the consistent power required for aftermarket HID systems, ensuring brighter, more reliable lighting every time you drive.

Maximize HID Performance

A relay harness is one of the most important components of any HID conversion. Even premium HID bulbs and ballasts depend on a stable power source for proper operation. The Morimoto H40 bypasses the limitations of factory wiring by drawing power directly from the battery, helping your HID system ignite faster, operate more efficiently, and perform consistently.

Benefits

• Delivers stable battery voltage to HID ballasts
• Eliminates flickering and intermittent operation
• Improves ballast startup and reliability
• Reduces electrical load on the factory headlight circuit
• Maximizes HID light output

Quick Plug-and-Play Installation

The Morimoto H40 is designed for a hassle-free installation with no cutting or splicing required. Its universal wiring layout and extended wire lengths make it compatible with most passenger cars, trucks, SUVs, and off-road vehicles.

Installation is straightforward:

• Connect the harness to the battery
• Plug into the factory headlight connector
• Connect your HID ballasts
• Mount the relays and secure the wiring

The result is a clean, OEM-style installation with dependable performance.

Universal Compatibility

The H40 uses industry-standard ballast connectors, making it compatible with virtually all aftermarket HID lighting systems.

Suitable for:

• HID low beam conversions
• HID high beam conversions
• HID fog light conversions

Note: Vehicles equipped with CANBUS electrical systems or pulsed Daytime Running Lights (DRLs) may require a Morimoto CANBUS or Mopar-specific relay harness.

Dual Relay Fail-Safe Design

Unlike many basic relay harnesses that power both headlights with a single relay, the Morimoto H40 uses two independent sealed 40A relays—one for each headlight. This provides greater reliability and ensures one headlight remains operational if a relay ever fails.

Each relay includes:

• Fully sealed weather-resistant construction
• Silicone weather seals
• Integrated flyback diode for back-EMF protection
• Weatherproof connectors throughout

Designed to perform reliably in rain, snow, heat, road salt, and other harsh conditions.

Premium OEM-Grade Construction

Built with high-quality automotive components, the Morimoto H40 is made for years of dependable service.

Features include:

• Heavy-duty automotive wiring
• Abrasion-resistant Techflex braided sleeving
• OEM-style sealed relay housings
• Polished stainless-steel relay mounting bracket
• Weatherproof electrical connectors

The finished installation offers an organized, factory-quality appearance under the hood.

Features

• Stable battery power delivered directly to HID ballasts
• Eliminates flickering and inconsistent HID operation
• Universal plug-and-play installation
• No cutting or splicing required
• Compatible with most aftermarket HID systems
• Suitable for low beams, high beams, and fog lights
• Dual independent sealed 40A relays
• Flyback diode protection for enhanced reliability
• Premium weatherproof construction
• OEM-quality fit and finish

Package Includes

• 1 × Morimoto HD Relay Harness H40
• Complete HID relay harness for one vehicle

Engineered for enthusiasts who demand reliable performance, the Morimoto HD Relay Harness H40 provides the stable power, premium construction, and long-lasting durability needed to get the most from any HID headlight or fog light conversion.