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What are the features of a PRO SERIES harness? 

  • Plug and play with very simple installation. The engine requires only 3 wires to be connected (starter signal, ignition signal and fuel pump).
  • No cores and additional wiring required.
  • Point to point tested on every wire.
  • Constructed using OEM connectors and TXL Automotive wire with OEM colors.
  • Made with high temp TXL wire (-40C to +125C operating temperature) with adhesive shrink tubing.
  • Wrapped in lightweight nylon loom with -94C to +257C operating temperature.

What does Plug and Play mean? 

Plug and Play originates from computer terminology. In the case of a Wiring Specialties harness it means that a harness installation is as simple as plugging it into the body of the car. Our plug and play harnesses include the necessary chassis and dash connectors. This makes the installation as OEM as possible - retaining practically all of the OEM functions.

What does No Core Required mean?

No core means that we do not require the customer to send any parts of their OEM or body wiring harness. We supply all the parts NEW and from our inventory. We suggest selling the OEM or original wiring to make some money back for the project.

What does Start-up Guarantee mean? 

Startup guarantee from Wiring Specialties means exactly that – our harnesses are guaranteed to work. With that in mind, we are only able to supply a part of the overall electrical system of the project (sensors, ECUs, body wiring, etc can be outside of our offering), but our commitment remains and we will do our best help you sort out any issues, even if they are not related to our harness.

PRO Series vs OEM Series – what is the difference?

Our Pro-Series is ideal for those looking for the best aesthetics, weight savings and reliability. 

  • It has an integrated transmission harness, and allows more customization when selecting options like ECU, injector and AFM connectors. 
  • It uses high-temp braided sleeving, and is built to exceed OEM specs for wire temperature rating, quality and power/ground routing.
  • The harness is designed from the ground-up for performance, optimization and modularity, and is 'Tucked' for a clean installation.
  • Developed in house on an actual engine to ensure a perfect fit to the engine and chassis.

Our OEM series is constructed in the same way the OEM factory harness is – with plastic loom and electrical tape. 

  • It is a top-quality, budget-friendly option with all brand-new construction and connectors – no core required. 
  • Main engine harness & transmission harness available separately for most applications, or as a discounted COMBO package.

I have a problem, what do I do?

Not to worry. We are available for tech support 7 days a week . Just pick up the phone and give us a shout during business hours and we can guide you through some tests. Alternatively you can email us any time at Keep in mind that reaching out to us before attempting any modifications or testing is a great way to keep the product’s warranty.

Do your harnesses carry any warranty?

Yes! All of our products are warrantied against defect and components failure. Our warranty will end if the product is modified by the user. Reach out to us if you have any concerns before doing anything else.

If I order the harness now, how long does it take to complete?

Unlike the competition, our harnesses are manufactured in larger quantities and are usually available for shipping within 1-3 days, depending on options selected for the harness.

Do you test your harnesses before shipping?

Yes! Each harness undergoes a point-to-point digital test. Each connector is connected to its test-mate and a computer confirms each connection and its destination. This process is utilized by the OEM manufacturers that build harnesses for our street cars

Do you build custom harnesses?

Yes! Every day. Just call us or email

Is a Wiring Specialties harness made differently from the competition?

Yes, we use an OEM style wiring construction process. We utilize hydraulic crimping machines that crimp wire and terminals with over 2000 lbs. of force. All of our harnesses undergo a wire-to-wire electronic test after assembly, to ensure that no wire pinout mistakes were made during assembly.

I don’t see my car listed.  Can Wiring Specialties help me?

Yes! Our Universal PRO harnesses are a perfect solution for the engine, and come with a self-contained pre-wired fuse/relay block for ignition, cooling fans and fuel pump. 

You just have to hook up start signal, fuel pump wires and a few other wires for tach and speedo, alternator warning light etc.     

Speedo and / or tach may need to have the signal adjusted using a frequency modulator (available as an add-on). You may have to run aftermarket gauges.   Not compatible with mechanical cable driven speedometers.

What is a Tucked harness?

Our PRO harnesses are designed to be routed more logically, around tighter angles and closer to engine and other components to give a minimal or ‘bare’ clean look.

What is a Grounding Kit?

Our Universal Grounding Kit ties a number if engine components to the body of the car. Our kit ensures that you will not have issues resulting from poor grounds. The Grounding Kit utilizes Ultra High temp fiberglass sleeving to allow installation under or around exhaust components.

What is the ECU Patch harness for?

The ECU patch harness eliminates the need to cut into your engine harness for accessories. Use the length of wire provided between the wiring harness plug and the ECU itself to install accessories such as air-fuel meters & controllers, electric boost controllers, rev/speed meters and more.

What is an alternator charge cable?

This ties the starter main power connection to the alternator main power connection for improved charging.  Similar to our Grounding Kits, this helps keep the power flowing correctly.

Can I use an ECU or Fuel injector options that are not listed?

Most likely – please contact us for specifics.

How does the Dakota Digital SGI-5 box make the speedo work?

This unit intercepts the signal from the speed sensor in the transmission and ‘conditions’ it. If your speedo reads half or double for example, this unit will allow you to adjust the readout to correctly display the speed.

Can I use LS2/LQ9 coil packs with this harness?

Yes! Wiring Specialties now offers LQ9/LS2 Plug and Play coil harnesses for RB and JZ series engines.