Downstream 02 Sensor wiring

Slimgoaty · Jan 4, 2012

The previous owner left me with a little surprise when it came to the 02 Sensor on my XJ. It was spliced with electrical tape and also running a universal sensor. Needless to say I had a code pertaining to my downstream o2 sensor and need some help. Coming from the main harness of my XJ I have a Green W/White, Black, Dark Brown W/Tan, and Dark Brown w/yellow. From my new 02 I have 2 white, 1 black, 1 grey.

I still have a connector that went from the jeeps harness that will connect to the o2 sensor but it must have been cut off another vehicle because the wires are not even close to the same color.

Wayne Sihler · Jan 4, 2012

Help us out... what year,motor,ect. There have been a few changes during the years..

Slimgoaty · Jan 5, 2012

Sorry, guess I have forgotten to edit my vehicle info on here.

1997 4.0 Aw4. 231

I dont really have access to a junkyard right now so I can't just go crawl unde one and look at it. From what I have discovered is that there is different colors on the harness's depending on year so I'm guessing that since mine is a early 97+ I might have the same color as a few years prior.

Matthew Currie · Jan 5, 2012

I'm not sure what help anyone can give unless you know the function of the wires on the new sensor.

The connector pinout for the 99 downstream sensor shows the following:

Cavity 1 - dark blue/white - fused automatic shutdown relay output (goes to Power distribution center fuse 24, via connector C-107 -shared with upstream sensor, same color)
Cavity 2 - black - ground
Cavity 3 - brown/yellow - sensor return (goes to PCM pin A4 in PCM connector C1 - shared with upstream sensor, same color)
Cavity 4 - tan/white oxygen sensor 1/2 signal - (goes to PCM pin A 25 in PCM connector C1)

The wiring diagram shows the wire to cavity 1 as dark green/white, just to confuse things.

It's possible that the input and output terminals of the new sensor are interchangeable. If that's the case, the best guess would be white for the two lines to the PCM, gray for the heater line from the ASD, and black for the ground.

I should add that if you're sleuthing out connections, the pinouts for both sensors are the same.
So even if you have no proper connectors any more, whatever color wire goes to pin 4 on the upstream sensor will be the one you want for the signal line on the other, the color at pin 3 is the return for both, and so forth.

scoobyxj · Jan 5, 2012

Matthew Currie said:
I'm not sure what help anyone can give unless you know the function of the wires on the new sensor.

The connector pinout for the 99 downstream sensor shows the following:

Cavity 1 - dark blue/white - fused automatic shutdown relay output (goes to Power distribution center fuse 24, via connector C-107 -shared with upstream sensor, same color)
Cavity 2 - black - ground
Cavity 3 - brown/yellow - sensor return (goes to PCM pin A4 in PCM connector C1 - shared with upstream sensor, same color)
Cavity 4 - tan/white oxygen sensor 1/2 signal - (goes to PCM pin A 25 in PCM connector C1)

The wiring diagram shows the wire to cavity 1 as dark green/white, just to confuse things.

It's possible that the input and output terminals of the new sensor are interchangeable. If that's the case, the best guess would be white for the two lines to the PCM, gray for the heater line from the ASD, and black for the ground.

I should add that if you're sleuthing out connections, the pinouts for both sensors are the same.
So even if you have no proper connectors any more, whatever color wire goes to pin 4 on the upstream sensor will be the one you want for the signal line on the other, the color at pin 3 is the return for both, and so forth.

I'm showing Cavity 1 as a DG/WT in color. Same function, but as Fuse 23 15amp
Also showing Cavity 4 as a TN/BK in color Same function.

Downstream 02 Sensor wiring

Slimgoaty

NAXJA Forum User

Wayne Sihler

NAXJA Member

Slimgoaty

NAXJA Forum User

Matthew Currie

NAXJA Member #760

scoobyxj

NAXJA Forum User

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