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3 wire O2 Sensor ? ASAP

Discussion in 'The Garage' started by Hossbaby50, Jun 18, 2005.

  1. Hossbaby50

    Hossbaby50 3/4 ton status

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    I picked up a 3 wire heated O2 sensor for my truck today. I am going to install it in the morning and have a question.

    There are 3 wires. 2 white and 1 black. The black wire is the sensor lead correct? The 2 white wires are the power wires correct. If I remember right it doesn't matter which white wire goes to a ground and which one is powered does it?

    Thanks
    Harley
     
  2. fortcollinsram

    fortcollinsram 1/2 ton status

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    hey man,

    on my 4-wire that I have yet to install I have 2 white wires, a grey and a black. I can't remember which is which but I know the color of the wires on mine had NO corelation to what their purpose was...Here is what I would do. Since you have a 3-wire, the o2 signal is still grounded through the sensor itself (in a 4-wire, the 4th wire is to ground the signal.

    Thread the o2 into the exhaust and start up the truck. Then poke the wires with a voltmeter. The one that puts out voltage is the signal wire. the other 2 are for the heater and it doesn't matter which is power and which is ground so once you figure out which is the signal, just hook a ground to one of the other and a 12v+ igntion switched to the final one.

    On my 4-wire, I bought the GM factory pigtail and the connector only goes on one way and each terminal is labeled (A,B,C,D) on the connector. Then I found the wiring diagram from the FSM and was able to determine which one did what.

    Anyhow, I will be working tomorrow at the south store (the Napa on 216 Horsetooth is now open on Sundays) so you should swing in.

    Later man

    Chris
     
  3. FWP

    FWP CRS

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    Chris has a good idea, you could do it that way.

    An alternative- Measure the resistance between wires before install. Do an ohm map of what the sensor looks like, electrically, and draw it out on paper. 2 wires will have low, less than 100 ohms (I'm guessing), those are the heater wires, polarity doesn't matter (it's just a coil of wire). The other wire will have some resistance, again, I'm guessing around 1K, to the case threads (gnd) of the sensor. HTH. Call if you need more help.

    BTW, How's life in CO going? You missed all the fun last weekend :o
     
  4. Mad-Dog

    Mad-Dog 1/2 ton status

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    that is correct..
     
  5. spearchucker

    spearchucker 1/2 ton status

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    What's the advantage of using a 3 wire over a one wire sensor?
     
  6. camiswelding

    camiswelding 1/2 ton status

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    Harley...
    I have done this exact conversion....
    black to sensor
    whites dont care....one to ground one to power///

    its on the cfm-tech website


    cam
     
  7. sled_dog

    sled_dog 1 ton status

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    Three wire has a heating element. O2 sensors need to be at a minimum of 600*F to work. Below that their reaction doesn't occur and you can't get a reading. The heater helps the O2 sensor get up to temperature quicker. Its not a big issue on a stock truck with a Y Pipe cause the O2 sensor is close to the manifold heat and the exhaust is restrictive. But if you place an O2 sensor downstream a bit(say right behind a long tube header), its not nearly as hot and has trouble getting up to temperature. In the case of my 89 Suburban, it never got up to temperature. I ran that thing in Open Loop mode for most of the time I drove it. Till I finally broke down and put a 3 Wire O2 sensor in, ran GREAT after that. Live and learn.

    And yes the white wires are the power and ground for the heater, doesn't matter which one goes to which.
     
  8. K5MONSTERCHEV

    K5MONSTERCHEV 1/2 ton status

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    What 3 wire sensor did you get? PN? Thanks.
     
  9. sled_dog

    sled_dog 1 ton status

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    hes using the "Bosch 13077". Hes having a bit of trouble with the engine at the moment and says the heated sensor didn't seem to be functioning properly. I used the same part number sensor with great results on my 89 Burb. I've often her people bad mouth the quality of Bosch products, I haven't had a bad experience myself but have talked to those who claim to have. This could well be one of those cases.
     
  10. K5MONSTERCHEV

    K5MONSTERCHEV 1/2 ton status

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    Haha, I am one of those to bad mouth them, lol.
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    I won't badmouth all Bosch stuff, just the O2 sensors. The MAF on my truck is original (stock on a Camaro) 80's vintage Bosch.

    Lots of stuff underhood of new GM's (and I'm sure others) is Bosch, just there has been a grounding issue with the Bosch O2's, it has been discussed on thirdgen.org, but is also in the diy-efi.org archives as well.
     

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