02 sensor question

tecate1987

94 chevy k1500 4x4 truck 4.3 engine.
has 3 wire 02 sensor in front of cat.
one wire is suppose to be heated, one signal and one ground.
can anyone tell me which is which or how to test.
The truck wires are one wire is purple, one red and one black.
I bought a universal 02 sensor and it has 2 white wires and one black ?
What wires go where?

Bigplanz

On a GM car, black is ground. If you go to Autozone's web site they probably have a wiring diagram for the truck.

tecate1987

thanks, I was on autozones web for a diagram.
They didnt have all the wires. There was a purple and a black. no red.
I am not sure how to tell from the sensor either, there are 2 white wires unlabeled. Does it matter where they go?

Bigplanz

Isn't there some sort of connector that clicks into place on the sensor? Like on an oil pressure sending unit, you disconnect the connector and connect it onto the new sending unit. Isn't the O2 sensor connected the same way?

tecate1987

no, the new wires of the sensor have to be spliced to the old connector.

Thurman

We do sell the "Universal O2 Sensor" but really don't like them, and that's one reason. We stock five (5) different "Universal" O2 Sensors. So, what does that tell you, their not so "Universal". Universal O2 Sensors come with different numbers and colors of wiring for different applications. I'm saying--You have the wrong sensor. David

zackinma

If you are installing a “universal” 02 sensor tht does not have a heater, it will not make your check engine light go away. 80% of the time an 02 sensor fails it is the heater, not the sensor. You may clear the code, but I promise it will return.
You can check the sensor with a multimeter by measuring resistance across the wires in and out of the sensor. The sensor does not have a ground wire. The sensor is grounded via the exhaust manifold. The 3 wires are: a constant 1 volt input, variable 0 to 1 volt output, and a constant 5 or 12 volts for the heater.