ORS 3RZ-FE / 2RZ-FE Conversion Wiring Harness

2.7L (3RZ-FE) and 2.4L (2RZ-FE) Adapter Wiring Harness -Stand-Alone Recipient

Install Instructions
Adapter Wiring Harness – Stand Alone Recipient: Installation Instructions

*****NOTICE TO CUSTOMER: If there is a problem suspected with the wiring harness, call ORS. DO NOT cut, alter, or dissect the ORS conversion harness. ORS accepts no responsibility for a harness that has been tampered with.

Please read all instructions before beginning work. If wire colors or connections described in these instructions do not match your specific application, please call ORS, we will gladly assist.

  1. ORS recommends the use of the 3RZ/5VZ battery harness for applications with the battery under the hood. This is the harness that connects the battery terminals to the starter and engine grounds in the donor vehicle. The alternator and starter wiring are also contained in this harness. If this harness is damaged or not available, ORS offers a conversion replacement for this harness, PN ORS-EC046 for 5VZ applications. Install this harness to the engine using the original configuration. Connect the engine ground cable and the starter terminal and cable. Connect the alternator connector and main lead. Route the battery harness underneath the steering shaft and up the driver side fender-well to the battery. Do not connect the battery terminals at this time. If using the ORS 3.4L Battery harness, refer to the provided ORS Battery Harness Installation Notes.
  2. Be sure the 3.4L/2.7L original engine wiring harness is properly installed on the engine and all connectors are plugged in. Route the engine harness lead behind the alternator and down the LH side of the engine and transmission. We highly recommend wrapping the harness with heat tape or exhaust wrap anywhere the harness passes close to the exhaust.
  3. Connect the engine harness to the oxygen sensor leads. Depending on your application, there may only be one oxygen sensor connector in the engine harness. If only one is found, the other is contained in the ORS harness and will be connected later.
  4. Route the engine wiring harness through the passenger side firewall and down to the kick-panel. Connect the ECU connectors to the ECU.
  5. Lay the ORS conversion harness near the RH kick panel. Orient the harness so that the leads are pointing in the proper direction
  6. Connect the 1 or 2 large connectors on the ORS conversion harness to the matching plugs on the engine harness, near the ECU. Connect the ECU connector on the ORS harness to the ECU (if applicable).
  7. Securely mount the relays in a safe location.
  8. Secure the ‘body ground’ terminal near this section to a suitable body ground.
  9. Route the harness lead containing the check engine light, diagnostic port, gauge leads, start and ignition leads, and brake switch lead toward the LH side of the vehicle, inside the interior.
  10. Route the main lead containing the fuse-holders, fuel pump leads, etc. out the RH firewall hole to the engine bay.
  11. Securely mount the ECU.
  12. Mount the check engine light and diagnostic port in appropriate locations in the LH interior area./li>
  13. Connect the “ignition on” signal to a small current ignition source. This will be a source that only provides 12V when the key/switch is in the ‘on’ and ‘start’ positions.
  14. Connect the “start signal” lead to a small current start signal source. This will be a source that only provides 12V when the key/switch is in the start position, often found at the ignition switch. M/T applications: If the ORS harness does not have clutch safety switch wires, and the use the vehicle’s clutch safety circuit (if equipped) is desired, use the start trigger wire coming from the original start relay instead of the start wire at the ignition switch.
  15. Splice the wire labeled ‘brake light switch signal’ into the switching side of the brake light circuit. This will be the side of the switch that only provides 12V with the brake pedal depressed. The brake signal is not required but recommended.
  16. With one-wire speed signal wire: wire to a 1-wire speed sensor signal. This can be provided from an after-market speed sensor designated for Toyota applications. This will be a square-wave signal, 4 pulses-per-revolution. Originally carbureted vehicles: refer to the supplement at the end of these instructions.
  17. With 3-wire speed sensor connector: Connect the ORS 3-wire speed sensor connector to the back of the transmission/transfer case. If using a trans/transfer case w/ a speedometer cable sender, use an electrical-speed-sensor adapter such as the one found through Marlin Crawler to adapt for plug-in. If the trans/transfer case had neither a cable or electrical speed connection, remove the corresponding hole-plug and install an electrical sender from a similar model. If unsure about this step contact ORS.
  18. The wires labeled “tachometer”, “water temp”, and “oil pressure” are signals for the corresponding gauges. Connect these leads to their proper gauge sender wire. Toyota tachometers may require soldering a 10k ohm ¼ watt resistor into the back to function with the 3RZ. Refer to provided illustrations. Originally carbureted vehicles: refer to the supplement at the end of these instructions.
  19. Important: If this step is not performed before engine is started, oil gauge damage may occur. Most 3.4L/2.7L vehicles come standard with an oil pressure switch to operate a light on the dash. Many older vehicles had a gauge in the instrument cluster, which used an oil sender. If the original vehicle has a gauge, replace the oil switch on the 5VZ/3RZ engine with the oil sender from the original (22R or 3.0L work) engine. It will thread straight in (but may require splicing the old connector to the engine harness). If a new oil sender is needed, Toyota PN 83520-34010 works very well.
  20. Under the hood, route the battery leads across the firewall and to the battery positive terminal. Remove the fuses and mount the fuse block/holders. Connect the leads to the battery positive terminal.
  21. If applicable, connect the EVAP leads to the appropriate EVAP components. ’96 and newer models use a newer EVAP system, a diagram is found at the end of these instructions for wiring and plumbing. ’95 models use EVAP plumbing similar to your original engine.
  22. Route the fuel pump leads down the firewall and under the vehicle to the fuel pump. Connect to the fuel pump as labeled.
  23. If applicable, route the “oxygen sensor” lead down the firewall. Route this lead to the secondary oxygen sensor (post-converter).
  24. If applicable: The lead labeled “to starter trigger wire/terminal” (under the hood) is ultimately connected to the smaller “trigger” terminal on the starter. This can be done one of two ways. 1) If using the 3.4L/2.7L battery harness: route the “starter” lead across the engine bay (in front of radiator), to the battery area. Cut the 4-pin connector from this harness (located near the battery terminals). Splice the wire labeled “starter” to the black wire in this connector. Be sure the connection is secure and sealed. 2) If not using the 3.4L/2.7L battery harness, route the “starter” lead to the starter. Directly connect this lead to the trigger terminal on the starter.
  25. If applicable: If no lead labeled “to starter trigger wire/terminal” exists, locate the vehicle’s original starter trigger wire (smaller wire connected to starter motor). Connect this wire to the new starter trigger terminal using one of the methods described in the previous step. If new wire is needed, use 14 gauge wire or thicker.
  26. If the ORS harness contains a lead labeled ‘to reverse light switch’, splice this wire to the original reverse light switch in the vehicle (as instructed by wire color); or directly to the reverse lights, positive side. If this lead does not exist, connect/splice the original reverse light switch connector to the reverse light switch on the transmission.

ALTERNATOR WIRING

When Using An Internally Regulated Alternator In An Externally Regulated System

  • Locate the wiring harness that connects to the newer alternator. This will be the battery harness on 5VZ and 3RZ applications. On 22R-E applications this harness will be a separate piece about 18” long, directly connected to the alternator. Connect this harness to the alternator and route this harness (if necessary) to the driver side fender-well area.
  • Find the original external alternator voltage regulator (IC Regulator) on the driver side inner fender-well area. Remove the regulator. The following steps refer to the remaining regulator connector.
  • Cut the appropriate wires from the original IC Regulator connector and splice the wires according to this chart:
    Original IC Regulator Connector—————————–Newer Alternator Wiring
    Smaller white wire———————————————Smaller white wire
    Red Wire——————————————————–Red wire
    Yellow Wire—————————————————-Yellow wire
    Large white cable———————————————-Large white cable
  • Most externally regulated models (normally ’79-’83) have a “charge lamp relay”. This relay is normally located under the dash near the steering column. It will be labeled accordingly.
  • If this relay exists, remove it. Cut this relay’s connector from the harness. Locate the yellow wire and the yellow w/ white stripe wire. Splice these 2 wires directly together. Insulate this connection.
  • Insulate the 2 remaining wires, but DO NOT splice them.

When connecting to an Internally Regulated System:

  • Cut the alternator connector from the Truck/4Runner vehicle’s original alternator connection. Splice the ORS sub harness leads to the vehicle’s alternator leads, matching wire colors (the white wire may be different thickness, this is OK).
  • SC400 models: The following 3 steps will generally apply. However, the alternator sub-harness connection is on the opposite side of the engine. A long alternator cable extension is also provided. Connect the ORS sub-harness and the alternator cable extension to the 1UZ alternator sub-harness in the RH-front corner of the engine. Then route the ORS sub-harness and cable extension across the front of the engine bay (along headlamp harness), in front of the radiator, to the LH fender area. Make the connections described below to the original (Truck/4Runner) alternator connector and cable. The alternator cable can be connected with bolts at the original eyelet, or in the small junction box on the LH fender. Be sure that the cable connections are well insulated.
  • Connect the ORS sub-harness to the Toyota wire harness on the LH side of the engine.
  • Cut the alternator connector from the Truck/4Runner vehicle’s original alternator connection. Splice the ORS sub harness leads to the vehicle’s alternator leads, matching wire colors (the white wire may be different thickness, this is OK).
  • Connect the vehicle’s alternator cable to the 1UZ-FE alternator cable on the LH side of the engine. One method is to simply connect the 2 eyelets using a bolt and nut. In this case, be sure to insulate this connection well. This can also be done w/ a splice connection.

When No Charging System Wiring Exists

  • Locate the wiring harness that connects to the newer alternator. This will be the battery harness on 5VZ and 3RZ applications. On 22R-E applications this harness will be a separate piece about 18” long, directly connected to the alternator. Connect this harness to the alternator.
  • The following will satisfy the alternator wiring:
    Red wire: “ignition on” 12V power – 12V when the ignition s/w is activated, fused at 10A – don’t give this constant power
    Small white wire: 12V battery power, direct connection to battery + terminal, fused at 7.5-10A.
    Yellow wire: ground signal for “charge warning lamp”. This provides a ground signal for a lamp in case of alternator failure.
    main alternator cable. This should be connected to the battery + terminal with an 80-100A fuse or fusible link in between.
  • If the battery is under-hood and re-located to the LH side: Find the power supply wire from the original fuse box, near the original battery location. This wire previously connected to the battery positive terminal. ORS offers an extension cable for this step, ORS-EC047. Using the ORS cable or 8-gauge cable, extend this power lead to reach the new battery location. If not using the ORS lead, be sure to install a fusible link of appropriate size at the end of this cable. Connect this lead to the battery positive terminal.
  • Be sure the power supply wire and “starter” leads that were routed in front of the radiator are loomed and properly secured below the radiator support. Excessive contact with the radiator when hot can damage this wiring. Use insulation or further fastening where necessary to prevent contact with the radiator.
  • Important: If this step is not performed before engine is started, oil gauge damage may occur. Most 3.4L/2.7L vehicles come standard with an oil pressure switch to operate a light on the dash. Many older vehicles had a gauge in the instrument cluster, which used an oil sender. If the original vehicle has a gauge, replace the oil switch on the 5VZ/3RZ engine with the oil sender from the original (22R or 3.0L work) engine. It will thread straight in (but may require splicing the old connector to the engine harness). If a new oil sender is needed, Toyota PN 83520-34010 works very well.
  • The ORS wiring harness pre-wires the vehicle’s tachometer. However, this tachometer will not work without modification (most cases). We have included an illustration that depicts soldering a 10k ohm ¼ watt resistor to the back of the tachometer; this solution was found on internet forums. We suggest searching pirate4x4.com, yotatech.com, or 4x4wire.com for instructions on this modification.
  • Go through all wiring and be sure that all wires are routed properly and securely fastened. Be sure that all wires are clear of exhaust parts, engine parts, and sharp edges.
  • Install the fuses.

Supplement for Automatic Transmission applications:
When using a late-model floor shifter

  • A late model floor-shifter assembly from the donor vehicle can be used with this conversion. The following steps pertain to wiring that shifter.
  • If the ORS conversion harness contains a lead labeled “to O/D switch”, skip the next step.
  • Locate the original connector for the O/D off switch on the center floor-board, near the shifter. The two wire colors necessary are normally yellow-green and white-black. Locate the 2 white wires from the overdrive switch in the new shifter from the donor vehicle. They will be routed from the shifter handle. Connect these wires to the original O/D switch wires. Orientation of these wires does not matter. These can be spliced directly, but we suggest using some sort of connector. Skip the next step
  • If the conversion harness contains a lead labeled “to O/D switch”, route this lead under the dashboard to the center floorboard near the shifter. Locate the 2 wires from the overdrive switch in the new shifter from the donor vehicle. They originate in the shifter handle. Splice these wires from the shifter to the ORS conversion harness lead (wires) labeled “to O/D off switch”. The switch is non-directional, wire orientation does not matter. If only one “O/D off” wire exists in the ORS harness, connect the second wire from the O/D off switch in the shifter to a suitable ground.
  • Locate the 2 wires that power the shifter assembly illumination in the donor vehicle’s shifter. Splice one wire to a positive illumination source in the interior (12V w/ tail-light switch on). Splice the other shifter illumination wire to the to the ground wire at the same source. A good illumination “source” is normally cigarette-lighter illumination or switch illumination.
  • Note: Starting in 2000, many models used a ‘momentary’ OD Off switch, which is not compatible with the older type switches. If the OD Off function does not work, the use of a ‘momentary’ style switch (matching year/model of the computer) may be required.

WIRING SUPPLEMENT
“STAND-ALONE” CONVERSION HARNESS
FOR 79-87 CARB. VEHICLES

  • Locate the original Emissions Control Computer in your vehicle. This is normally in the passenger side kick-panel. Disconnect and discard this computer.
  • Locate the following wires in the connector to the Emission Control Computer. Cut the wire from the connector and directly splice to the wire lead in the ORS harness according to the chart below.
    Emission Control Computer——–ORS Harness Lead
    Wire Color
    -Green w/ blue stripe ——————– To + speed sensor signal
    -Black ————————————–To tachometer