Downstream 02 sensor wire matchup

Need help on matching my O2 downstream sensor wires to female harness. Sensor wires are 2 black , 1 blue and one white. Harness wires are 1 blue, 1 white with a seperate internal ground, 1 brown andb1 green. Also if I'm splicing what do I do with bare internal ground by white wire in harness

 

Sounds like you have the newer sensor and your truck uses the older wiring harness.

Older pre-2012


Newer 2013+


I going to take a guess and say the black wires are ground.
But let’s let @Muddinfun and @Jimmyh take a look.

 

This is the message that the OP posted to my profile. This sheds a little more light on the subject, but the only thing I know is that the bare wire is a grounded shield to protect the signal from electrical interference. That's all I've got.

"Hey my 2012 reg cab 4cyl Tacoma downstream 02 sensor and female harness that the 02 plugs into got chewed by dogs. I have 2 blacks wires in O2 sensor and 1 white and 1 blue, on my harness I have 1 brown, 1 blue, 1 green and a white with a bare stranded wire by it but separated by insulation do you know how wires wire together and what do I do with stranded wire which I'm assuming is a ground of some sort"

 

Yes the Bare Sheath is a Electronic Noise Shield as stated above and indicated by the dotted line around the White Signal Wire OX1B and should connect to the brown Ground wire.

It also seems that the black wire is a ground on the 2013 + years into the ECU and if connected to your 2012 harness will go to the brown Ground wire E2 and should work just fine.

White wire OX1B = Signal Wire to ECU.
Green Wire HT1B = Heater Signal to Heated O2 Sensor.
Black Wire ( EX1B on 2013+ Brown Ground E2 on 2012 ) = Ground wire for O2 Sensor Heater.
Blue Wire +B = + Power to the sensor.
Brown Wire = Shield Ground Wire.

Stranded uninsulated sheath = Electronic Noise Shield.

I hope this helps somewhat.

 

A bit of an old thread but if anyone can help - I have a P0137 code and am chasing it down. I posted about it here but just want to confirm what to do with the unshielded bit of wire? It was just covered with electrical tape, is that how it should be?

 

You need not do anything with that bit of shielding wire. That end is not connected and should not be connected. The other end is or should be connected to chassis ground. If you want to verify that it is connected to ground check it to ground with a DMM meter.

 

leave as is as jimmy has implied. Connecting at both ends can cause circulating currents and noise in the system.

 

Commonly called a ground loop and is an undesired condition which could cause all kinds of crazy symptoms.