have the stock o2 with blue white and two black wires. it doesnt have a harness so I am going to run the wires straight to ecu I have looked at a few pin outs but the exact color of the wires that each need to be spliced would be helpful. its a 1991 5 spd

 

Are you sure the wires aren't under the drivers seat?

 

Get yourself a copy of the Factory Service Manual (search this site for download locations for FSM) and use it. There is a category for wiring, select that and then select "engine wiring control" for your motor size (4 or 6 cyl). You will see a wiring diagram with the four wire location connections as well as the wiring routing.

 

I did check under seat only harness is on passenger side looks like for gas. I also have a manual but would like toknow what color the wire for o2 is thanks

 

If you would take a moment and download the FSM, you would be able to see the wiring colors like this:

 

sorry im on a xell phone im still looking for the link

 

http://www.ncttora.com/FSM/

 

lopkin aat that the red n white wire provides thee 12v signal?

 

Did you download the FSM? It has all the information you are asking. If you are trying to trace wiring, then check for continuity from the correct pin in the connectors for the computer (passenger side kick panel) to the O2 end of the wiring and verify that there is close to 0 on the meter.
If you are creating a new wire harness, follow the FSM diagrams and connect the 4 wires up to the 4 connection spots as seen in the diagram. I had to run a new wire for mine and I used a 4 wire shielded cable that I bought by the foot from Home Depot. I then ran each wire to the correct pin on the computer. Download the FSM, go to the 3VZE "engine control" section under "complete wiring / electrical" (E.W.D. 1990-1995::1995 4runner: Engine Control (3VZ-E)) and print out the three wiring color pages. Tape the three of them together, and follow along with the wiring to see where each wire goes. Some of the wiring branches out to more than one location, or is in conjunction with another sensor / signal item. Crimp connections together to verify that it is working, then go back and solder them. Get heat shielding casing for the wiring that is going underneath the vehicle.

 

yes and you have been a major help I did download them but wiring and color codes just arent my thing. I am trying to create a new harness amd will take.a look once I get home. from what I see red n green and pink and green will be the two heaters

 

I found the orginal wires I have a pink n green white n red a black n brown my o2 isnt stock it has one blie one white and two black any ideas

 

With the above images from the FSM, we know that the B is white/red and the HT is Pink/Green. What does the connector on the non-stock O2 sensor look like? What color is in the B position? What color is in the HT position? If I had to guess, I would say that the two blacks would go on the bottom two ports of the connector. If I then had to guess for the other two, I would guess that the white would go to the white/red, and the blue would go to the P/G. (I think the P stands for Lima - a shade of blue)

Disclaimer - This information is for your use only, is expressed as an opinion, and is in no way what so ever the responsibility of the author if it is not correct. The best way to be sure that you do not burn up something is to go and get the correct New O2 sensor with the correct wiring plug, and then you will not "let the smoke out".

 

how would the truck run if the o2 wasnt working I ordered a denso and will be here.tomorrow. I am starting to think my cam timing is off a tooth so if the o2 doesnt work im try that

 

I just bought a direct fit denso it has a blue a white and two black wires on bottom but since my oem plug is gone and I cant find the first yota in the junk yard does anyone know what wire goes to what. I know most of you guys could look under your truck since denso is so poular mine is a 91 thanks in advance

 

 

thanks for that ima assuming if I flip my plug over on the denso o2 it will be the same?

 

That is an example of the Denso plug facing you, with the color of the wires that go to each port of the plug exactly as you see it facing you.

 

ok thanks so much wiring just confuses the hell out of me but ill def dry that when I get home

 

so after replacing the o2, wires, cap and rotor my truck is still running really rich. only known problems is a really bad leak between the header and exhaust pipe. could be tricking the o2 but I doubt it. were should I start.