Beating a dead Horse. 4.3 1998 blazer 4x4

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Apr 8, 2024 | 07:59 PM
  #11  
Quote: 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).
  1. 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.
  2. 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
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Apr 8, 2024 | 08:11 PM
  #12  
You have to be careful with the wattage of the bulb used because the current can be too high and damage the computer drive circuit.

George
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Apr 8, 2024 | 08:14 PM
  #13  
Quote: You have to be careful with the wattage of the bulb used because the current can be too high and damage the computer drive circuit.

George
We ran these on 9volt batteries. Amazon says they are 5v .765watt bulbs. Bulb is a 502.
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Apr 8, 2024 | 08:23 PM
  #14  
An incandescent test light is 2-6 watts so your bulb won't load the circuit as much but should work. Its safe to use in any event.

George
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Apr 8, 2024 | 08:34 PM
  #15  
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.
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Apr 8, 2024 | 08:36 PM
  #16  
Go back and read post #10
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Apr 8, 2024 | 08:40 PM
  #17  
Im sorry, I screwed up the harness colors. The heater wires are black and pink. The sensor wires are correct in post 10
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Apr 8, 2024 | 08:42 PM
  #18  
I corrected post #10.
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Apr 8, 2024 | 08:52 PM
  #19  
Quote: I corrected post #10.
Okay black and pick I have no light with truck in any state.

I put the old O2 back in...... Maybe it was a bad connection and my NEW O2s are DOA?!
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Apr 8, 2024 | 09:31 PM
  #20  
Regarding no power on pink and black, check the Oxygen fuse 20a in the UHFB.

What was the result of test 2 in post 10?

George
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