Relay Box for Power Windows / Locks

(2 customer reviews)

$165.00$215.00 (USD)

MGI’s specialized relay box is designed for power windows and power doors with minimal wiring involved. Use 2 relays for each power window motor, and 2 relays for locks.

  • Pre-wired with 4 or 6 SPDT Bosch-style relays rated 40A
  • Built-in 5amp LED control fuse that glows when blown
  • Allows for negative switching if needed
  • #6 bolt-size screw terminals are labeled for easy wiring

For use with 2-wire door lock actuators only.

BULK ORDERS – please contact for availability.
BULK ORDERS – please contact for availability.


Reliable High-Current Control
for power windows and door locks


Custom wiring done right. Adding relays can become a complicated and messy project. That’s where MGI steps in ⁠— our fused relay boxes provide centralized control and protection with minimal wiring involved.


Wiring is made easy. Each relay box comes with a red main feeder cable and labeled screw terminals. Use the Wiring Diagrams to help connect your power windows and locks. It’s that easy.


Quality is Guaranteed. Our relay boxes are routinely tested, with relays rated 40A at 12 volts. You get premium parts only, including an aluminum frame pre-wired with high-temperature GXL.

Relay Box Wiring Diagrams
how to install power windows and locks with relays


Wiring Diagram

Study the wiring diagram to familiarize yourself with the relay box and its components. You’ll need to choose between positive or negative switching for each pair of relays.


Window & Lock Switches

relay switches

Connect your window switches and main power to the appropriate screw terminals on the relay box. Repeat for power locks.


Connect to Motors

relay box wiring

Connect your power window motors and lock actuators to the appropriate screw terminals on the relay box. Connect the black ground wire (with red ring terminal) to the auto chassis.

what comes with every power window / door relay kit

  • Aluminum frame and 4 or 6 built-in relays
    • 40 AMP rating
    • 5-pin SPDT style allows for reverse motor operation
  • Integrated 5A LED control circuit fuse
    • ATC / ATO style blade fuse with LED light that glows when blown

Answers to Popular questions

Why buy a relay box for power windows?

It’s all about custom wiring done right — power windows and power locks need pairs of relays to operate properly, which can be a real hassle with stand-alone relays. Our power window relay boxes make wiring easy, convenient and centralized, with added features such as built-in LED fuses and the ability for negative switching.

Can this relay box operate “normally closed” devices?

Yes! Power windows and doors need pairs of N.C. 5-pin relays for reverse motor operation. Our unique SPDT Bosch style relay boxes are specifically designed to connect power windows and locks. All you need to do is connect your switches and power windows / locks to the appropriate screw terminals. See the wiring diagrams for more information.


2 reviews for Relay Box for Power Windows / Locks

  1. Tim Takash (verified owner)

    Tim Takash

  2. Paul K (verified owner)

    After speaking with an MGI engineer and reviewing your
    website I thought I was dealing with a quality company.
    I recently ordered over $1,000 of your products, some of which arrived damaged. The items I ordered were just thrown loose in a box with no secondary boxes or even any packing material. The metal boxes punched through the shipping box (which was taped up by the postal service) and while moving around had broken several fuses and relays. I was grossly disappointed and am livid that I spent my $ with a company that cares so little about the products they produce. All the other parts I’ve ordered for my car came carefully packaged and in perfect condition. I’m having the damaged items repaired locally because I don’t want to deal with your company ever again. I’ll be passing along my experience to others.

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Before finalizing your purchase

It is important to familiarize yourself with the MGI panel Installation Manual. Not only does this help you to select the appropriate options for your race panel, it will enable you to tackle any troubleshooting issues with confidence.