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02 sensor blues

Discussion in '4th Gen 4Runners (2003-2009)' started by lizardman1, Nov 5, 2019.

  1. Nov 5, 2019 at 6:15 AM
    #1
    lizardman1

    lizardman1 [OP] New Member

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    Hello, I am new to this forum and have a question about my 04 4runner, it is 2wd with a 4.0.
    What I have is a P2241 code: Positive current control circuit low bank 2 sensor 1. I have replaced both upstream sensors, but the code still comes back. I checked the harness to the ecm and found the wiring for the bank 1 upstream sensor has been repaired. The repair looks solid and I think the problem may be with the ecm. IMG_20191104_123101966_BURST000_COVER.jpg
    This is the connector for bank 2 sensor 1, I back-probed the wires and came up these results
    Black/wt stripe +12V
    White, no voltage and no ground, both of these wires control the heater for the sensor. The wires for the heater are both black on the sensor.
    Brown wire + 3V. White wire on sensor
    Yellow wire + 3v. Blue wire on sensor
    The other connector for bank 1 sensor 1 had no repairs and had the same readings as bank 1 sensor 1.
    According to Denso The color codes for the sensor are:
    Black/Heater both wires
    White/Earth "ground"
    Blue/Signal+
    I hope someone here would know what the values are for the wires I just checked. In addition I checked the original sensors and found the heater circuits were reading roughly 2.4 ohms no opens found with them.
     
    Last edited: Nov 5, 2019
  2. Nov 5, 2019 at 8:25 AM
    #2
    Benny123

    Benny123 Toyota enthusiast

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    Southeast Charlotte, NC
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    2016 Nautical Blue SR5 Premium
    LEDs all around, otherwise bone stock.
  3. Nov 5, 2019 at 8:47 AM
    #3
    lizardman1

    lizardman1 [OP] New Member

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  4. Nov 6, 2019 at 3:55 AM
    #4
    lizardman1

    lizardman1 [OP] New Member

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    I have figured out the o2 sensor problem. The PO had been taking the vehicle to a Toyota dealership in Scottsdale, I found this out by going to Toyota's website, they provided me with the Po's service history. Turns out it had previous troubles with emission codes, once in Sept of 18 and again in Oct this year, both involving wiring repairs to the o2 harness. I took a better look at the repair and found this.IMG_20191105_114038227.jpg
    This is what caused the P2241 code!! I called the dealership and told them what I found, they told me to bring it in and they would fix it no charge, GREAT! I went there right away, they brought it into the shop immediately and started on it. Two hours later it was done and at no charge to me, but here is where it takes a turn...
    See wiring schematic
    IMG_20191105_172721753.jpg
    Bank 2 sensor 1 (A13) in the schematic shows White wire +B and Black/ White stripe wire as Heater which is correct, obviously those two wires were crossed shown in the first pic. The service adviser told me that the wires were crossed intentionally by the tech because they were in the wrong pin locations to begin with. The pin locations are CORRECT as per the wiring diagram. There is no way that this vehicle would have been driven since new and this problem was only corrected in October this year WTF! The reason in the first place for the previous harness repairs was rodent related and NOT a factory fault. What a bunch of BS.
    I will check the wiring today and verify if they left it alone and just covered it back up or if they uncrossed the two wires and lied about it to cover their mistake.
    To back their claim of the wiring issue they told me they had to perform a Zero Point Calibration to turn off the check engine light. From what I have read about that, the ZPC is done to clear the VSC/TRAC/TRAC OFF and ABS lights in the early gen 4 up until mid 05 because of the non CAN protocols. The check engine light is off for now, but I will have to plug my scanner in to check the monitors before going to emissions and possibly trigger the VSC lights. At least I now know how the correct that issue.
     
    Last edited: Nov 6, 2019
  5. Nov 6, 2019 at 4:39 AM
    #5
    Benny123

    Benny123 Toyota enthusiast

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    2016 Nautical Blue SR5 Premium
    LEDs all around, otherwise bone stock.
    wow. Interesting. Would not have figured that would be the case. Glad you not only tracked the history down, but that Toyota was willing to help. Makes you wonder if the sensors you swapped were actually good.

    Glad you took that cover off!
     
  6. Nov 6, 2019 at 10:48 AM
    #6
    lizardman1

    lizardman1 [OP] New Member

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    Both sensors passed the resistance test as per Toyota's service bulletin. I think they were not the problem in the first place.
     
  7. Nov 16, 2019 at 12:30 AM
    #7
    audio

    audio New Member

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    Great debugging!
     
  8. Nov 16, 2019 at 9:28 AM
    #8
    4x Old Guy

    4x Old Guy New Member

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    Big-O Bigfoot A/T tires
    Great work!

    Back in the day as a motorpool mechanic, we had a Ford Granada that always ran like c*** and went through spark plugs like nobody’s business. We finally purchased an automotive oscilloscope and hooked it up and found that the spark waveforms were 180° off polarity. According to the wiring schematic color codes, the primary side of the ignition coil was hooked up correctly. After further investigation we discovered that the wires had been reversed back up in the wiring harness from the factory. We reversed the polarity of the coil connectors and voila! It ran like a bat out of h*** and no longer ate spark plugs.
     
  9. Nov 16, 2019 at 9:49 AM
    #9
    4x Old Guy

    4x Old Guy New Member

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    Big-O Bigfoot A/T tires

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