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There is no value in looking at the O2 sensor voltage if it is not installed in a running warmed up truck. Hopefully you have an incandescent (not led) test light (scope on a rope, old school).
First we need to make sure that the heater circuit is getting powered so that the sensor can heat up and become operational. The two wires that supply power to the simple resistive heating element are usually the two that are the same color, brown in your case. I am referring to the harness colors not the sensor pigtail colors, those colors are whatever the aftermarket sensor guys says they are. Disconnect the sensor and connect your incandescent test light to those two wires in the harness and see if it lights up. If not, turn the key on, if not, start the truck.
Keep the sensor unplugged and get your scanner and live data up and running. That sensor should show a steady 0.45v ish volts. Then ground the test light clip, touch the probe end to battery voltage to prove a good probe ground and then touch the ppl/wht wire in the harness and see if the scanner voltage drops to zero ish. That will prove the integrity of the signal wire from the engine computer to the harness connector.
Report back and we can go from there.
George
Sadly I had one of those years ago... I might have a bulb pigtail from my last job laying around if that would work? Not a hand unit but it's redneck. Is there anything I can use on a Klein mm300? Will this work haha
Last edited by GrilledCobra; Apr 8, 2024 at 08:02 PM.
If I go from brown wire to ground I get nothing and the .445 does not change on live truck Should I touch the brown wire to another color? I have pink, black, ppl/white, brw/white.
