O2 Sensor Wiring (1 Viewer)

brettk

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Knoxville, TN
The previous owner for whatever reason decided to cut one of the O2 sensors at the harness. Fortunately I was able to snag the last of the NTK OBD1 sensors from Joey, I’ve got a housing and terminals on the way from Mr T...but I’m not sure which wires from the harness match up with 02 sensor wires. Would someone be so kind as to match the wires for me? Search yielded some results, but the wire colors weren’t a 100% match.
1994 1FZ. Thanks!

Harness Side:
Yellow/Red
Blue/White
Black/Yellow
Gray

O2 Sensor:
Blue
Gray
Brown
White

0B556003-6EF7-42EE-B160-553441AF44B1.jpeg
 
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Aug 2, 2020
Messages
182
Location
Bay Area Ca
I literally went through almost this exact issue! Cut out mounting points for O2 sensors and the whole thing... it was due to the fact of the bolt melting and welding to the bolt. But either way there are wiring diagrams that I used to wire the harness back to the sensor. There is also another option, if the replaced the mount with a thread like in my case.
 

brettk

SILVER Star
Joined
Apr 6, 2020
Messages
155
Location
Knoxville, TN
I literally went through almost this exact issue! Cut out mounting points for O2 sensors and the whole thing... it was due to the fact of the bolt melting and welding to the bolt. But either way there are wiring diagrams that I used to wire the harness back to the sensor. There is also another option, if the replaced the mount with a thread like in my case.

Do you still have those wiring diagrams?
 
Joined
Aug 2, 2020
Messages
182
Location
Bay Area Ca
Do you still have those wiring diagrams?

Found them online, google-fu the maker of the sensor and the wiring colors your working with. I found them for Denzo, NTK, Toyota (oem) etc. it will be dependent on the manufacture. That said, two wires typically will be for the heater readings, in my case they were black, then one for the sensor o2 data and then one ground. If you have the FSM it lists the spec for the harness that comes from ECU, so you can test there and identify which is which. Then match the wiring diagram your specific sensor and match to the harness. (Sorry, typing on my phone while on a Zoom meeting :)
 
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Jun 26, 2004
Messages
1,894
Location
east coast Canada
The previous owner for whatever reason decided to cut one of the O2 sensors at the harness. Fortunately I was able to snag the last of the NTK OBD1 sensors from Joey, I’ve got a housing and terminals on the way from Mr T...but I’m not sure which wires from the harness match up with 02 sensor wires. Would someone be so kind as to match the wires for me? Search yielded some results, but the wire colors weren’t a 100% match.
1994 1FZ. Thanks!

Harness Side:
Yellow/Red
Blue/White
Black/Yellow
Gray

O2 Sensor:
Blue
Gray
Brown
White

View attachment 2457554

does this help?

mine pic shows the colours and the other one shows the HT and +B pin locations

00609F39-6F27-41FB-AA5F-E7C8FC63B3F2.jpeg


2E512F5E-0CA2-44BC-BF2A-7137BE7B2384.jpeg
 

brettk

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Joined
Apr 6, 2020
Messages
155
Location
Knoxville, TN
And get some better butt splices than those

That’s perfect!! Thank you so much. The butt connectors are from the PO as well. I’m gonna cut about a half inch above them because the wires look a little burnt as you can see in the picture. Run better connectors, heat shrink, and loom it to make it look nice.
 

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