I need to splice in a 4-wire O2 sensor in my 99 Blazer.

My harness O2 wiring has (2) Dark Brown, (1) Tan and (1) Purple wire.

The O2 sensor has (2) Black, (1) White and (1) Blue wires.

It's obvious the Dark Brown and Black wires correspond.

What about the other (2) wires ?

 

What are you driving?

 

Personally I'd suggest you get the correct sensor. It's not a simple as it seems (the blacks/browns). The tan is a sensor high, purple is sensor low. The two browns: If you look at the truck side harness you'll see one is a 12v+ pink, one is a black ground. Probably the heating element will work no matter which way you wire the polarity (two browns), but the other two WILL determine if it generates a positive or negative voltage. Did it come with any kind of a diagram or wire labeling?

 

1999 Blazer.

No. I bought it from the Classifieds on here. It was off an 2002 Blazer.

Will it do any harm if the +/- get hooked up backwards ? I should know if it works or not if the CEL goes out.

 

The wiring colors are the same for my 2000 and your '99. I don't know what they are for an '02, wait for Swarlkk to reply before cutting any wires, he probably could tell you whether it'll work or not with the additional info you provided him and tell you how to wire it. If you get the 12v feed wrong it could hurt the computer, it's expecting less than 1 volt to come back on the sensor lines

 

DO NOT cut the wires! The sensor breathes through the wires. Just get the proper sensor or you'll be wasting time and money.

 

Swartlkk is right, any variance in resistance will throw off the values. if you cut, splice or solder the wires together there will be a change in resistance, most likely adding more resistance therefore changing the values going thru the wires. it would not matter on the heating element + or -, but it would throw off the sensor high and low input and output values to and from the PCM

 

Thanks for the info guys.

I researched through many wiring diagrams and found the colors did in fact change from my 99s starting in 2002.

I'll just go buy a new one with the correct adapter already in place.

 

Can you send me the link the wiring diagram for a 2000 blazer that you found.
I am dealing with a P0135 code that i cant fix. Any help would be awesome.

 

I searched and came acrossed this thread, but I want to verify that what I found is correct. Can someone (swartlkk?) verify the following information:

• o2 side tan wire = sensor high/12v+
• o2 side purple wire = sensor low/gnd
• o2 side browns = heater wires (truck side pink = 12v+ and black = gnd)

This information would be very much appreciated!

Thanks