I am trying to wire in a new rear o2 sensor and was wondering what the original wires go to. I have a black, white, brown, and green wire. Which ones are the heater wires? Ground wire? I know a OEM replacement would be easiest, but my 4runner doesn't have the connector, so I would have to splice it anyway. Any help on this would be appreciated. Thanks!

It's for a 2001 toyota 4runner 3.4L.

 

what brand sensor is it? are these wire colors coming off the sensor or the 4runner wiring harness?

im only finding black,black,white and blue

 

Trying to install a bosch replacement sensor. The wires that I mentioned ( black, brown, green, and white) are what are coming off the 4runner wiring harness, not the replacement part.

Is it possible that the wires have discolored or faded?

 

what color wires are on the sensor? this is the only pic i can find with wires like yours. like you said they might be discolored..

 

The wires on the Bosch replacement part are :white, white, black, and gray. I found a post where on the Bosch part, the white wires are heater wires, the gray is the ground, and the black is the o2 signal wire.

I'm going to assume that my wires have discolored, and should really be black and blue instead of brown and green.

By looking at the pic in the previous post, I'm going to guess that the two black wires are the heater wires, but which one is the signal wire?

 

According to my FSM for the '02 4runner the wire colors are:
Green/yel = Heater
White/yel = Heater
Blk = Signal
Brown = Sig Ground

So the Bosch wires should match up to:
Sensor -> Truck
White ->> Green
White ->> White
Black -->> Black
Gray --->> Brown