ORS 1GR-FE Engine Conversion Wiring Harness



It is important to read full product description before ordering:

The Off Road Solutions 1GR-FE Engine Conversion Wiring Harness will aid in a 1GR-FE (1GR) engine swap into an older vehicle. This wire harness will plug directly into the 1GR ECU (computer) and engine control components, and will connect to the recipient vehicle by plug in or simple splice connections. This wire harness will replace all existing 1GR engine and transmission wiring.

The Toyota 4.0L 1GR-FE replaced the 3.4L 5VZ as Toyota’s Truck/SUV V6 engine. It features 4.0L displacement, 24-Valve DOHC, Variable Valve Timing and Aluminum Engine Block and Heads. Output is approximately 240-270 HP and approximately 265-280 ft-lb torque (depending on year and model).

The 1GR-FE (4.0L V6) fuel injection system is different and more advanced when compared to older Toyota vehicles. The biggest differences in the engine control circuit are the addition of Variable Valve Timing and Electronic Throttle Control (ETCS – drive-by-wire). The Off Road Solutions 1GR Engine Conversion Wiring Harness will contain the donor vehicle’s engine and transmission control circuits in your older vehicle for use with the 1GR ECU and components.

From the factory, the OEM 1GR Engine Control and Transmission Control circuits were built into various wiring harnesses:

  • 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 (ECU) and then to the body harness.
  • The remainder of the 1GR Engine and Transmission Control circuits were built into the body wiring, along with the rest of the vehicle’s circuits. The body wiring includes the “under-dash” harness, the engine-bay harness (including fuse box), and even the wiring to the rear. About 40% of the 1GR Engine and Transmission Control wiring was contained in the body wiring.

The ORS 1GR Conversion Wire harness will contain the entire Engine and Transmission Control circuits in one all-new harness. This means the ORS harness is a little larger than the original 1GR engine harness, but this simplifies the conversion.

We also accommodate 2 main recipient vehicle types; this is the vehicle receiving the engine:

  • Our ” Fuel-Injected” version (22R-E/3VZ/5VZ/2RZ/3RZ Vehicle) is for ’85-’95 Truck/4Runner and ’93-’94 T100 vehicles that originally had the 3.0L 3VZ-E engine or the fuel injected 22R-E, in addition to 95-04 Tacoma and 96-02 4Runner models. This version requires that the original body wiring and fuse box is still in place and will plug directly into the body wiring for a simple install. Very little splicing is required to install this version; it is nearly 100% plug-and-play. The original body wiring in your older Toyota will not require dismantling, and this version will accommodate your OEM gauges (tachometer will require some additional work during the install), speed sensor, reverse lights, 4×4 system and 4×4 indicator lamp.
  • Our “Stand-Alone” version is designed for virtually any other 12volt vehicle. It works well with carbureted vehicles, other makes, and some race/custom vehicles. This version requires that the vehicle has at least a basic electrical system already in place. This basic system must include: start and ignition switch, charging, fuse/battery and gauge circuits. This will connect to the recipient vehicle through a few simple splices. Note that the Stand-Alone version includes a fuel pump power/control circuit. Note: if your vehicle has no wiring body wiring at all see our Monster Harness.

We offer 2 options regarding the transmission:

  • Manual Transmission: Use this option when using a manual transmission. This includes an application where the donor or recipient vehicle was originally auto and the engine setup will now be manual.
  • Automatic Transmission: Use this option when using a Toyota automatic transmission, from the donor application. This includes an application where the recipient was originally manual but is now being converted to an automatic transmission.

Transfer Case Control: If using a transfer case that utilizes electronic control and/or center differential lock, an additional circuit will be required in the engine harness to connect to and control the transfer case. See the drop-down. If a fully manual transfer case is in use, select N/A.

ECU Programming, Immobilizer: Some 1GR-FE donor applications were equipped with an Immobilizer system, often called a “chip key”. The simplest way to use this donor ECU application in a swap is programming the ECU to remove the immobilizer function. See the drop down.

ECU Programming, M/T applications: When doing a swap into a Manual-Transmission application, it is ideal to use an ECU from a M/T-based donor application. The use of an A/T-based donor ECU, used with a Manual Transmission, will generate trouble codes (engine light). It is normally easier to locate an ECU from an A/T donor application. In this case, an A/T ECU can be programmed to mask A/T-related trouble codes for use in an M/T application. See drop-down.

This product is built per order, please allow 6-8 weeks for order completion. This time can vary by season; if completion time is crucial, please contact ORS before ordering.

Notice when ordering: Please include the following information in the “Order Notes” box or a separate email when placing your order. If sending a separate email be sure the name on the order will be obvious.

From Donor Vehicle:

  • VIN, only if 100% certain of engine origin, OR part numbers requested below
  • Toyota ECU part number (8966x-xxxxx)
  • Original donor Toyota engine harness part number (82121-xxxxx), this is found on a paper tag near the ECU connections.
  • Model Year
  • Model
  • 4WD or 2WD
  • Manual or Automatic Transmission

From Your Vehicle:

  • VIN
  • Year Model
  • Model
  • Original Engine
  • Manual or Automatic Transmission (originally)
  • Indicate specific transmission to be used in conversion
  • Shifter to be used (for A/T models)
  • 4WD or 2WD
  • If 4×4, indicate transfer case application, original to transmission or changed
  • Front suspension type (original or modified)
  • For 89-95 Truck, 90-95 4Runner, Indicate if ADD (Auto-Hub) system is in use
  • Swapped battery location
  • OEM (original-type) tachometer in use?

Core Connectors for 22R-E/3VZ-E recipient type:
For some applications we will need a core connector from your vehicle. If your vehicle is an ’85-’90, we need one core connector. This may also be the case for some 2RZ/3RZ/5VZ applications. It is found on the original recipient ENGINE harness, near the ECU connectors. There are the 1-3 connectors that join the engine harness to the body/dash harness, one of these is needed. Once an order is placed, we will send a picture of the connector needed and a label file (for print) that can be used to send the core connector in a USPS Small Flat Rate Box. Cut the connector needed from the ENGINE harness w/ 1-3″ of wire lead. Note: we will fill the core connector fill w/ new wire terminals.


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