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    Sale!

    Holley Dominator EFI J4 Auxiliary Harness, 26 Programmable I/O | 558-404

    Vendor: Holley EFI
    Part Number: 558-404
    Save $30
    Sale Price $238.95 Regular Price $268.95

    Available to order. In-stock orders typically ship in 1 to 2 business days.

    Not sure it fits your vehicle?
    Email sales@berryperformancesales.com with your year, make, model and engine, and we'll help you check fitment before you order.
    Fast Fulfillment: In-stock orders typically ship within 1 to 2 business days.
    Free Shipping on Orders Over $99 | Excludes freight shipments
    International Shipping Available: email sales@berryperformancesales.com for a quote.
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    This J4 auxiliary harness connects to the Dominator EFI J4 ECU connector, giving builders 26 user-programmable inputs and outputs. Note that the J4 connector is also used for transmission control applications, so confirm which auxiliary connector your build needs before ordering.

    Specifications:

    • Connector: J4
    • Programmable I/O: 26 user-programmable inputs and outputs
    • Harness Type: Auxiliary
    • Part Number: 558-404

    FAQ

    What is the J4 connector used for?

    It provides 26 user-programmable inputs and outputs on Dominator EFI, and is also used for transmission control applications.

    How many programmable I/O does this harness provide?

    26 user-programmable inputs and outputs.

    Should I order this or the J3 harness (558-403)?

    It depends on your build's I/O needs and whether you're using J4 for transmission control — check your Dominator EFI wiring diagram to confirm which connector your application requires.

    Shipping Policy
    • Free shipping on orders over $99 (excludes freight shipments).
    • In-stock orders typically ship within 1 to 2 business days. Weekend and holiday orders are processed the next business day.
    • Orders ship from Defiance, Ohio and a nationwide network of warehouses and manufacturers.
    • Items showing an ETA are not in stock yet. ETAs come from the manufacturer and can change.
    • No P.O. Boxes. International orders need a shipping quote, so email us first.

    Read the full Shipping Policy

    Return Policy
    • 30-day return window from the ship date. Returns must be approved first; email sales@berryperformancesales.com with your order number.
    • Items must be unused, complete and in the original packaging.
    • A 20% restocking fee applies, and return shipping is paid by the buyer.
    • Not returnable: installed or modified parts, opened or used programmers and tuners, custom orders, Open Box, and Clearance or Final Sale items.
    • Damaged, defective or incorrect items must be reported within 48 hours of delivery with photos.

    Read the full Return Policy

    Disclaimer

    All products are sold for off-road use only unless otherwise specified. Buyer assumes all responsibility for installation and operation. Seller is not liable for any incidental, indirect, or consequential damages — including engine failure, labor costs, or vehicle downtime — resulting from the use of any product sold.

    By making a purchase from Berry Performance Sales, you acknowledge and agree to abide by the terms and conditions of these Policies.

    For any questions or concerns, please contact us — we’re always happy to help.

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