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Allright. The sensor produce from 0 to 1 volt. The sensor produce the voltage right. It’s not the computer who send a reference and pickup a signal. So what he is doing is grounding the signal so 0 volt is recognize by the computer. And 0 volt is a lean condition (lots of oxygen)
On the other end, to produce 1 volt, you could do you own montage with resistor to produce 1 volt. If you supply 12volt you will fry the computer (motherboard, print circuit) as the computer has it’s own tolerance. By using his own body you actually are the resistance and you still have voltage (it is probably over 1 volt). If we would use a multimeter on each side of his hand you would seen the actual voltage send to the pcm.
That is just 1 of the easiest and most cost effective way to test the wiring and pcm…. as long as you have access to that connector
I completely agree with your point about this being a quick and inexpensive test. I’m just not so sure I’d ever be comfortable enough to touch the positive…even if it is a 12V setup.
I have seen a few videos by the technician, all have been easy to understand and I think a good explanation. By making himself the resistor he is creating a voltage divider/pull up resistor. There will be about 1 volt from the oxygen sensor wire to ground. In theory he will dropping about 11 volts dc across himself. It would be interesting to place a dc voltmeter across him and see if in fact that is the case. I’ve never seen this done before, but it obviously works. By doing that you are testing the PCM to see how it reacts. Then by grounding the circuit you are forcing the circuit to the other extreme and seeing how the PCM reacts. It looks like a good test of the computers reaction to an extreme rich and extreme lean condition. Then by using propane to force the actual sensor with a overly rich mixture you are testing the sensors ability to react. I would think you would create an actual lean condition to test that but he just grounded the sensor, unless I missed something. I wish my scan tool could show multiple windows like that, it makes it much easier to understand.
https://www.powerprobe.com/hook.php
The most expensive tool (500$) you can actually send specific current amperage as well as voltage. That is actually a great tool as wide band sensor are operating on 5 volt circuit so you can actually go on the signal wire…. choose 3.5 volt for instance … and go double check with a scanner if the computer see what you apply.
You should do the test with and multimeter and see what you get from the left to the right hand going from 1 pole to the other.
I have done O2 sensor testing the same as in the video many times. I have also tested the voltage supplied when touching battery positive and it varies from car to car. I’m not sure why exactly but it might be humidity. Sometimes the voltage is as high as 1.4 volts but usually is around 1 to 1.2 volts.
Never fried a computer yet though.Seems us “old guys” can still git-ur-dun.
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