ORS “Stand-Alone” 3.4L Conversion Harness




Please see the ‘notice’ located below description before ordering.

The ORS “Stand-Alone” Harness greatly simplifies the electrical portion of the 3.4L engine conversion.

The wiring is possibly the most complicated part of this conversion. The 5VZ-FE (3.4L) electronics will have to be in installed in your vehicle to make this engine swap possible.

There are 3 primary parts of this OEM 5VZ fuel injection circuit. The first is the engine wiring harness. This is the harness that is primarily attached to the engine. This is sometimes called the injector harness. This harness connects the engine components such as the fuel injectors, ignition coils, air flow meter, etc. to the engine computer and the body harness.

The second part is the Engine Control Unit, or ECU. This is also called the Engine Control Module, or ECM. Sometimes it is just called the engine computer. This is the heart of the fuel injection system. This maze of solid state circuitry uses various input signals and outputs to control the engine.

The third part of the 5VZ electronic fuel injection circuit is the body harness. This is sometimes called the “dash” harness or the “main” harness. It stretches across the inside of the dashboard and sometimes into the engine bay. This harness is the largest harness in the vehicle and carries the majority of the vehicle’s circuits. About 40% of the 5VZ fuel injection’s wiring circuit is contained in this harness.

The engine wiring harness and ECU are easy to install in another vehicle when performing this swap, but the real challenge comes about when it’s time to take care of that last 40%. This is where ORS Conversion Harness comes in. Our conversion harness is designed to provide that last 40% of the 5VZ fuel injection wiring circuit. This harness connects directly to the 5VZ ECU and engine wiring harness; then uses simple splice connections to connect to your existing wiring. The existing wiring in your vehicle will not have to be torn apart or changed in order to accommodate this new engine. The ORS Conversion Harness will also include the necessary emission equipment wiring for your application. Additionally, this harness is designed to accommodate basic gauges, will include a malfunction indicator lamp, and come equipped with any necessary switches.

The alternative is to re-wire your entire vehicle with a newer body wiring harness. The ORS conversion wiring harness is designed save you an enormous amount of time and potential trouble.

NOTE: This harness is designed for any application. However, a basic electrical system must already be in place (starting system, charging system, switched ignition, gauges, etc.) If no electrical system exists at all, check out our Monster Wiring Harness.

This product is built per order, please allow 1-2 weeks for order completion.

“Donor Vehicle” options refer to the engine harness application.

Notice when ordering: Please include the following information in the “Order Notes” box when placing your order:

From Donor Vehicle:

  • VIN, only if 100% certain of engine origin, OR-
  • Toyota ECU and engine harness part numbers (8966x-xxxxx & 82121-xxxxx)
  • Model Year
  • Model
  • 4WD or 2WD
  • Manual or Automatic Transmission

From Your Vehicle:

  • Year Model (if applicable)
  • Model, or general description of custom vehicle
  • Manual or Automatic Transmission (originally)
  • Indicate specific transmission to be used in conversion
  • If using 3.0L version of Auto Transmission, indicate transfer case to be used
  • General location of engine computer (ECU)
  • Any other details that may pertain


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