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Morimoto DIY Relay Kit

1 Review

Brand: Morimoto




PART #: 1 x WP310

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Morimoto offers high-quality 4-pin automotive relays designed for building custom relay harnesses. These relays are not only cost-effective but also feature three layers of silicone seals, providing protection against the elements. With an industry-standard layout including switch, ground, power input, and power output, they offer versatility in various applications. These relays can handle 12V at up to 40 Amps through their copper coils and feature an integrated flyback diode to prevent back-feeding. Morimoto's relays are the same reliable components found in their HD Relay Harness, allowing users to create professional-grade harnesses, and optional brackets enable the combination of multiple relays for a clean, customized setup.


  • High-Quality Relays: Morimoto offers 4-pin automotive relays.
  • Weatherproof: Features three layers of silicone seals for reliability in all conditions.
  • Standard Layout: Includes switch (85), ground (86), power input (87), and power output (30).
  • Powerful Performance: Handles 12V at up to 40 Amps with a built-in flyback diode.
  • Easy Customization: Standard in the HD Relay Harness, with optional brackets for flexible mounting.


  • RELAY: 1x 4-Pin Relay + Shell

  • BASE: 1x 4-Pin Inlet

  • SEALS: 2x Upper + Lower

  • CONTACTS: 4x Coated Copper

  • OPTIONAL BRACKET: 1x Hanging


This product includes a 1 Year limited warranty, serviced and supported by our team in Atlanta, GA. This warranty does not cover modifications, alterations, or misuse. For additional information, contact us.


  • Capacity: 40A @ 12V DC

  • Power Capacity: 600w

  • Wire Needed: 14-16AWG





DIY: These high quality 4-pin automotive relays are great for spares or for those looking to build their own relay harness. Don't bother spending two or three times as much for the same thing, or getting less for the same amount of money. Buy Morimoto.

Protected:from the elements with 3 layers of silicone seals! Don't trust unsealed relays under the hood that are prone to fail due to moisture. These things are basically impenetrable both rain or shine.

Industry Standard: layout includes the switch (85), ground (86), power input (87), and power output (30)

Internally: they are rated to pass 12V at up to 40 Amps through their high quality copper coils. Integrated flyback diode prevents potential back-feeding.

Standard: Equipment on the HD Relay Harness by Morimoto, you can now build your own harnesses like the pros.

Optional: brackets allow you to combine two relays together on a single mount for a clean setup that designed around more than one relay.

Ratings & Reviews

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The Highest quality Relay Harness I have ever seen!


These relays came with the 9006 and 9005 HD Wiring harnesses that I purchased for my truck. I'm very impressed with them. They are very high quality. The relay feels very tough and the seals seal up tight! If you shop around you will not find a nicer automotive relay out there. I will be ordering these for other automotive projects in the future!

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