oxygen sensor wire identification

[tim98]

Need a little help. For a 87 TC setup with LA2. I have to make my Oxy sensor connector from scratch because my harness does not have one. The problem is the schematics only show the one wire that goes to the cpu pin 29. Can someone show me on the sensor itself exactly which wire goes to ground, to key on power, and the sensor wire. Thanks guys

 

[TireIron]

what wire colors does your sensor have on it? and how many?

 

[srteach]

You know that the wire metals have to be the exact same in order to not create current, don't you? If they are different metals, the wire will have a current of its' own.

 

[tim98]

The sensor has three wires. Two black, one white.

No i did not know about the wire current, but I'm using standard copper wiring.

On second thought that does not make sense. What about the wire differences through the wiring harness all they way to the CPU. There is no way that is the same exact all the way through.

 

[TireIron]

The wires connected to the sensor are special wire, but the wire from the connector all the way to the ecu is just standard copper wire. You will not be able to solder directly to the O2 wires, they tend to not conduct heat... I would recommend setting it up with a factory connector anyway for ease of changing.

On that 3 wire sensor, the white wire is the signal wire and the 2 black wires are the heater wires. connect one heater wire to a good ground point and the other to the heater control power, normally an ignition controlled fused 12V source, it doesn't matter which black is power and ground.

The reference ground for the signal runs through the sensor housing into the exhaust to the engine. On a 4 wire sensor it would have an extra ground wire for this that would be connected to a separate clean ground point (not the same wire for the heater ground) but that doesn't matter on your 3 wire sensor...

 

[tim98]

Thank youtire iron. I actually have the factory connector, it just needs to be rewired. I'm not cutting the wires on the sensor itself. Thaks for your help everyone.

 

[srteach]

On second thought that does not make sense. What about the wire differences through the wiring harness all they way to the CPU. There is no way that is the same exact all the way through.

The different wire type changes throughout the wire harness are accounted for. If you add another dissimilar metal joint or two (O2 wire to splice/solder, splice/solder to socket wire is two connections), they are not accounted for in the sensor system, and can throw off the ECU calculations.

Same thing happens in any sensor network. It's called the Seebeck effect, and is the same principle as the Peltier effect, used in a different way.

 

[tim98]

Ok, I got ya. Two disimialar metals in line with each other, different temps will produce a magnetic field. Had to look it up but I know what your getting at. Thanks.

I will not be cutting the sensor wires.