Availability
Holley Sniper offers transmission-specific controller harnesses for a variety of GM and Ford automatic transmission models. The plug-and-play harnesses are pre-terminated with j4 connectors. Order the harness recommended for your EFI application.
Not Yet Reviewed
$269.95
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$299.95
The long wire runs of an electric pump installation can sometimes result in a voltage drop at the pump. Holley fuel pump relay and harness kits offer good insurance that the fuel pump will be receiving full voltage from the battery. The kits can be used with any electric fuel pump, as long as the current load is not above 30 amps. They work with 12, 16 and 24 V systems and come equipped with 12 AWG that provides extra current-carrying capacity with minimal voltage loss. A 30 amp relay is included with a relay socket wired with extra-long leads specifically designed to reduce the number of splices required. Quality insulated crimp connectors are provided to make necessary splices where required and detailed installation instructions are also included.
( 8 )
$170.95
Holley split wire looms direct from the Holley EFI Wiring Shop. These are high-quality TechFlex F6 black nylon braided split looms they utilize on their main harnesses. They are available in two lengths and a range of diameters from 1/8 in. to 2 in. to build or service your Holley EFI-powered machine.
( 31 )
$14.44
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$137.95
Holley Terminator EFI HyperSpark ignition adapters are designed to plug-and-play with HyperSpark distributors and Holley EFI main harnesses with an ignition connector. They enable you to run a "timed sequential" fuel strategy for faster responses and cleaner emissions. Complete the improvement of your driving experience with a Holley Terminator EFI HyperSpark ignition adapter.
( 1 )
$46.09
Holley trans-brake input protection modules allow for an ECU input to be safely connected directly to the 12 V side of the trans-brake solenoid. They are designed to protect the ECU input from damaging fly-back voltage, which occurs when the trans-brake is released. Not using one of them will cause damage to the ECU over time.
( 4 )
$59.25
Holley J2A, J2B, J3, J4 connector and pin kits are designed for use with your Holley Dominator EFI system. These kits include four connectors and pins for the connectors.
Not Yet Reviewed
$219.95
For an uncluttered, hassle-free LT engine swap, Holley EFI Terminator X drive-by-wire throttle body wiring harnesses are the solution. Designed for Gen V LTx throttle bodies and Terminator X and X Max ECUs, the harnesses are built with pre-terminated ends to make your install easier. Build your project to take advantage of DBW benefits with the help of Holley EFI's drive-by-wire throttle body wiring harnesses.
Not Yet Reviewed
$283.95
Holley GM transmission wiring harnesses are designed to work in conjunction with Holley Dominator EFI fuel injection systems. These application-specific complete terminated harnesses come with a J4 connector to operate General Motors electronic transmissions. For all of your transmission management systems and accessory needs, go with Holley.
Not Yet Reviewed
$280.95
It's always a good idea to place a safety switch in the circuit when installing an electric fuel pump. Holley safety fuel pressure switches will ensure the electric pump will not work unless the engine has oil pressure. It will prevent the pump from running in a situation where the motor may stall with the ignition on. Wiring the switch through the starter solenoid circuit energizes the pump on engine start-up. After the engine is running, the switch continues to provide power to the pump as long as there is oil pressure to keep the switch turned on.
( 18 )
$53.49
Holley shielded cable conductor wires are great for wiring up EFI systems or for any wiring job requiring heavy-duty 20-gauge wire. Each cable is internally shielded for maximum noise rejection and come in a variety of different sizes.
( 3 )
$45.55
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$249.95
Holley EFI tachometer input ignition adapters are for applications using a CD Box, such as an MSD 6AL, while not using timing control. They're designed for use with Sniper 2 EFI systems and external ignition control boxes with tachometer signal output. Not for direct connection to coil.
Not Yet Reviewed
$28.01
Holley LS extended-length main engine harnesses are 22 in. longer than previous harnesses. Designed to fit most 24x and 58x LS engines from 1997-2012, they are a perfect fit for installers wanting to mount any Holley EFI ECU inside of the passenger compartment where it is away from the elements, and easy to access, such as on a roll bar or under the passenger seat. Notes: * Plug-and-play with Dominator, HP, Terminator X, and Terminator X Max ECUs * LS1/6 harness interfaces with 24x crank and 1x cam sensors * LS2/3/7 harness interfaces with 58x crank and 4x cam sensors
( 1 )
$672.95
Want to fully rewire your Holley EFI installation? Or perhaps you're starting a new build, and want to wire everything perfectly the first time. Holley EFI unterminated main harnesses come with both J1A and J1B connectors fully terminated—with 15 ft. of flying lead wiring to allow you to completely customize your main harness installation. Features include: * J1A and J1B terminated connectors * 60 crimped wires: (57 of 20-gauge wire, and three 18-gauge wire) * 15 ft. long flying lead harness * 30 optional plug seals
Not Yet Reviewed
$425.95
Holley has you covered with their extensive line of OE-style wiring components, including connector terminal pins to help you build or service your Holley EFI-powered machine. These pins are available in a variety of styles for different connectors and wire gauge. From replacement connectors and pins … to wire loom and tools—make Holley your one-stop solution for all of your wiring component needs.
( 4 )
$21.18
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$65.85
Holley's Terminator X and Terminator X Max ECUs give you complete control of your engine, self-learning fuel strategies, and the race-winning technology of Holley EFI at a budget-friendly price. When you need to service your system, Holley has the components that will fit and perform as expected. Holley Terminator X/X Max engine control module wiring harnesses allow you to access the inputs and outputs built into the Terminator X or Terminator X Max ECU. These harnesses have all eight pins populated, four inputs and four outputs. Features: * 36 in. flying leads * Pre-terminated at ECU connector * Eight wires * Sealed connector
( 2 )
$39.49
On Sale
You already have the wire and Holley EFI ECU connector kits have the rest of what you need to rewire your EFI installation. Fully terminate your own custom main harness with Holly EFI ECU connector kits. Features include: * Pre-terminated J1A/J1B Tyco Superseal connectors * 20 to 22 gauge pre-terminated wires * 16 to 18 gauge pre-terminated wires * Cavity plugs
( 3 )
$52.69
$28.98
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$158.95
Choose EFI main power wiring harnesses from Holley to meet your needs. Several choices are offered—TBI, LS applications, multi-point, and un-terminated harnesses—to feed and carry your engine's electrical supply. Get wired for electronic fuel injection with Holley EFI systems main wiring harnesses.
Not Yet Reviewed
$574.95
Want to make the switch from the original Sniper EFI to Sniper 2 and don't want to rewire your system? This harness is designed to do exactly that! The Holley Sniper adapter harness is a plug-and-play solution to connect your existing Sniper 1 wiring harness to a Sniper 2 throttle body! It can be used with any Sniper 2 system that is not equipped with a power distribution module (PDM). Simply remove your Sniper EFI throttle body from the intake manifold, unplug all of the connectors, and plug the Sniper EFI 2 adapter harness into your existing main harness. Cycle your ignition key, run a fresh wizard on the display of your choosing, and enjoy the benefits of Sniper EFI 2. Make the switch to Sniper 2 in minutes! Sniper EFI 2 is a high performance electronic fuel injection system designed for a wide range of engines and horsepower goals. It provides improved engine performance, better fuel efficiency, and easier starting, making it the perfect upgrade for any enthusiast looking to take their ride to the next level. With its easy installation and advanced technology, the Sniper EFI 2 is the ultimate fuel injection system for any conventional V8 engine. Features: * Update your Sniper 1 to Sniper 2 in less than an hour: One-step, plug-and-play upgrade from your existing Sniper EFI install to a Sniper 2 throttle body * Eliminates the need to rewire your existing Sniper EFI installation * The wiring harness included with the Sniper 2 kit will not be used. This adapter is intended to be used with the original Sniper EFI wiring harness and new Sniper 2 EFI throttle body Sniper 2 EFI benefits: * (NEW) Next Generation ECU features improved RF noise and interference resistance (stands up to old car wiring, noisy alternators, faulty plug wires)  * (NEW) "Hidden Harness" wiring harnesses exit from the rear of throttle body for a clean appearance  * (NEW) Inputs and outputs consist of: 2x ground inputs, 2x ground outputs, 1x TPS output (0-5 V) and 1x tach output  * (NEW) Next Generation mil-spec style M8 positive lock connector for CAN1 and CAN2 provides the latest in CAN bus technology for a simple yet robust connection 
( 2 )
$56.09
Holley EFI Pro-Billet ignition adapters allow for plug-and-play ignition timing control when utilizing an MSD Pro-Billet distributor and Holley EFI main harness with an ignition connector. The adapters are ideal for use with Terminator X electronic fuel injection.
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$39.24
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$39.49
Holley wiring harness connectors provide one-stop shopping for your wiring needs. Along with their extensive line of wiring components, Holley offers a tremendous assortment of genuine OEM connectors to hook up your wiring project properly, securely, and completely. They're available individually and in packs of 10—with most including pins, seals, and TPA. Finish wiring your Holley-powered machine with their quality wiring harness connectors.
( 9 )
$9.06
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$52.69
Holley offers I/O connector kits for J1A through J4 connectors. These wiring replacement parts mean you no longer have to buy a complete connector kit if you only need one I/O connector. They offer OEM quality and are perfect for DIY or wiring specialists that want to build custom wiring harnesses.
( 1 )
$52.69
Holley EFI Dominator transmission harnesses provide control of your Tremec. The harnesses are terminated for VSS, reverse lockout, and reverse lights. Choose the one designed for your build.
( 1 )
$228.95
Holley drive-by-wire throttle body wiring harnesses are designed for use with the Holley Dominator ECU, as well as the factory drive-by-wire throttle body. These harnesses feature pre-terminated connections, ensuring true plug-n-play installation.
Not Yet Reviewed
$474.95
Holley EFI CAN adapter harnesses are available in several options. Offered are male to female harnesses in several lengths for Racepak and other external CAN devices, harnesses that adapt 2-pin Holley main harness CAN connectors to newer 4-pin CAN devices, and kits that directly connect Racepak Vnet/Holley to either the J1A (HP and Dominator ECUs) or J3 (Dominator ECU only) connectors. Create secure connections with genuine Holley EFI CAN adapter harnesses.
Not Yet Reviewed
$92.19
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