O2 sensor circuit

Discussion in '1995 - 2004 Toyota Tacoma' started by de 203996, Jun 29, 2018.

  1. de 203996

    de 203996 New Member

    My truck is a 1999 tocoma regular cab 2.4 engine ..had a code PO 135.. replaced upstream sensor with Denso...code came back..checked at connector..had 12v on plus side and no grd from computor key on.The wire from grd at o2 sensor is purple with black stripe...think at ECU a wire that color is at E8 # 2 wire but no continuity from ecu to sensor both unpluged..am i right for wire from ecu or did i miss it..looking at info for differant models this wire should be a straight shot.can anybody verify the ecu pin # for heated grd wire for O2 sensor..dealing with #1 and 2 wires at sensor
     
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  3. OR17TRD

    OR17TRD Well-Known Member

    Bogunn, kp.taco and whippersnapper02 like this.
  4. OP
    de 203996

    de 203996 New Member

    It is an automatic trans also
     
  5. Bogunn

    Bogunn Well-Known Member

    This is totally a Nancy question.
     
    OR17TRD likes this.
  6. OP
    de 203996

    de 203996 New Member

    Found my problem..........
     
    OR17TRD likes this.
  7. OR17TRD

    OR17TRD Well-Known Member

    ...and...
     
  8. Bogunn

    Bogunn Well-Known Member

    The suspense is killing me.....
     
    OR17TRD likes this.
  9. OP
    de 203996

    de 203996 New Member

    Was right on the color of # 2 pin at ECU... jumpered that wire to Ox senser and then got a PO 125 code quick......took jumper back off and got PO125 and PO 135...replaced ECT sensor which helped nothing...traced wiring as far as i could in both directions..checked O2 sensor i bought and it was correct.....then i found it....light pull of wires on top of trans gave me all 4 wires going to front O2 sensor in my hand..took connector to auto trans off and harness came out far enough to see Mr squrrel's eating through split loom ,tape and wires through copper in a 1/4 area
     
    OR17TRD and Bogunn like this.
  10. OR17TRD

    OR17TRD Well-Known Member

    Damn you mr squirrel! Glad you figured it out. Sounds like a PITA.
     
  11. Bogunn

    Bogunn Well-Known Member

    Wow. That was some work.
     

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