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Thread: O2 sensor (84-87)

  1. #1
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    O2 sensor (84-87)

    Hey i just bought my van a couple weeks ago. its running rich and when i located my o2 sensor on my exhaust, the other end thats supposed to plug in somewhere is just dangling. i cant find anywhere where it would plug in! can someone point me in the right direction please?

  2. #2
    Van Enthusiast blakebecker37130's Avatar
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    Re: 86 Toyota van o2 sensor

    Hello,

    Is the wire hanging and not connected to the 02 sensor, or is the wire connected to the 02 sensor and not connected to the harness? When looking at the wiring diagram the sensor wire runs back to the harness which runs back to the ECU. The harness branch is close to the air meter and mine had a brittle grey vinyl tube covering the 02 sensor wire. I just did this repair on my 86. When I bought the sensor, I thought the parts store sold me the wrong one. The one they supplied had male threads on the sensor. It turns out my van is registered as an 86 but actually has the 87 build as far as the exhaust, so it takes the single mesh shielded wire 02 sensor with the oval flange, gasket and two nuts. Also the previous owner or technician had broken the connector on the 02 harness branch, so a splice, solder, silicone waterproofing and electrical tape connection was made to complete the branch to 02 sensor circuit. An important thing to know which is not shown in the diagram is that the mesh shield wire needs to be grounded in order for the 02 sensor to complete the circuit. When I repaired mine, I discovered the mesh shield wire was corroded and not making a good ground, causing a check engine code 05 (opencircuit in 02 sensor). I had to strip the circuit back about 6-8 inches to find good mesh shield wire. I soldered a new circuit to this and grounded it on the intake manifold near the air meter, where some other circuits are factory grounded with terminals. This solved the issue and the light has stayed off and the van runs much better. I hope this info helps.

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    Best regards,
    Blake

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    Re: 86 Toyota van o2 sensor

    The other side of the connector is near the air filter box, toward the steering wheel on the engine side. It will be the only one that fits the 02 sensor, sporting a single conductor and a plastic tab to help glide it in.

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    Re: 86 Toyota van o2 sensor

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    im just not seeing anything where it would plug in. it seems like itd be very obvious, but nothing, and near the airbox, im assuming you mean right in this area right?

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    Re: 86 Toyota van o2 sensor

    if anyone is able to show me a picture of where the o2 sensor plugs into the electrical, i would be totally stoked. sorry im new to this van, love the thing just trying to figure out everything! thank you so much! also i found this cut wire (coming out of split casing) that was hanging down toward where the o2 sensor is. maybe somebody cut off the old one, never spliced on new one? i dont know. wire looks to be about the same size as the one connected to the o2 sensor. Name:  wire.jpg
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  6. #6
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    Re: 86 Toyota van o2 sensor

    It looks like you are holding the correct wire in your last picture because there is no connector attached The 02 sensors from 84-87 that were single wire commonly broke off right at the plug.

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    Re: 86 Toyota van o2 sensor

    JPERL might be correct. I'll try to snap a photo of the connector for you and upload it when I get home.

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    Van Enthusiast blakebecker37130's Avatar
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    Re: 86 Toyota van o2 sensor

    The picture of the hanging wire looks like the mating conn for the 02 sensor? This circuit should just run up into the branch on the harness and go back to the ecu. The junction is right in that area by the airflow meter. Follow the hanging conn circuit and see if it is broken? It might belong to the branch you pictured with the YAZAKI stamp on it? If so make sure that when you repair it that you also pay attention to that shield wire I noted in my first reply. Please see the attached pic of what the factory spec connector looks like on my van.


    Name:  02 sens 87.JPG
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    Best regards,

    Blake

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    Re: 86 Toyota van o2 sensor

    ok i figured out whats going on. the male end of the connector, broke off at the wire, and was inside the female end of the connector that is on the opposite side of the wire of the sensor itself. i guess i look for a male end connector peice at the parts store and splice it on. thats what its seeming like...

  10. #10
    Van Enthusiast blakebecker37130's Avatar
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    Re: 86 Toyota van o2 sensor

    I could not find one of those connectors at in my local parts stores. They may be available online? I'm sure you can find one at the salvage yard on just about any old Toyota, 1980's vintage. I opted to do as the technician did before me and hardwire the circuit. No more connectors. I grounded the mesh shield wire to the intake manifold where a series of factory grounds were already established. I then ran a single wire down to the 02 sensor and hardwired it by splicing, soldering, silicone waterproofing the splice and finally wrapping the splice with electrical tape. I then utilized some zip ties to pull the slack out of the way of the exhaust system and to keep it from coming loose or catching on something. I trust this repair just as much as the factory connection, if not better. I work for a big name Japanese wire harness supplier and am not at all worried about hardwiring connections. If the 02 sensor fails, I'll cut if off like a rotten banana and start over again

    Best regards,
    Blake

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    Re: 86 Toyota van o2 sensor

    so what i did is bought a new sensor put it in, and spliced it into the wire that i am 90 percent certain the male end connector broke off of. it seems to be running alot better and definitley more power. i am still getting a code 5 tho. does it have to be driven for awhile for the codes to reset? i am also getting code 11. im still trying to figure out what you're talking about when you say the mesh wire and it needing to be grounded. the sensor i have is a single wire and and its nothing more than a stardard looking wire.

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    Re: 86 Toyota van o2 sensor

    got it taken care of, figured out how to reset codes! no more code 5! now to take care of the code 11.... thanks everyone

  13. 01-18-2017, 03:29 PM

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    off topic and bad advice!

  14. 01-18-2017, 03:48 PM

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    off topic and bad advice!

  15. 01-18-2017, 04:11 PM

    Reason
    off topic and bad advice!

  16. #13
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    o2 sensor replacement

    o2 sensor replacement is pretty easy. You can purchase a direct replacement with the plastic connector plug already attached ($15 plug and play version)...or go the cheaper $6 version that requires you to cut off the old the connector plug from the old o2 sensor you will remove (leave a couple of inches of wire sticking out of the connector plug) and crimp the new o2 sensor to the old connector. A new gasket should be used to avoid an exhaust leak in the near future.

    Safety first...be sure the car is in park or in gear, engage the emergency brake, look up behind the driver side front wheel, and you should spot the o2 sensor. It is held by 2 nuts. There is also a heat shield held by the 2 nuts. Follow the wire coming out of the o2 sensor to the connector plug. It is mounted up higher, but should be easy to access, even without raising the van on jack stands.
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    Oxygen Sensor Special Service Tool. Still available?

    O.K so I got a code 5 that indicates Ox sensor, the manual tells me how to check with voltmeter but it's says I need SST 09842-14010 does anyone know where can I find one? Or an EFI Checker SST09991-00100 ? The other questions I have is. Can I just pin the nidles to connector if so I would need a little more clarity if someone can help wich of the 3 connctors is it? I had same problem identifying for the check engine test. The thing is that the manual shows on pictures of the 3 and they look pretty similar at least the two larger ones. Any help is appreciated Dogger562
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    Van Addict AD2101's Avatar
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    Re: Oxigen Sensor Special Service Tool. Still available?

    I think this is one of those situations where you just pony up the $25 and get a new denso o2 sensor. I've never even heard of that SST but can almost assure it'll cost more than the sensor itself (if you can find it) and it's one of those catch 22's where it makes more sense to buy the part without troubleshooting further. If the SST says the o2 sensor is no good then you still need to buy the sensor and if it says the o2 sensor is fine (doubtful), then you're still out the price of the SST, so either way the cheapest route is just to buy the sensor and forgo trying to hunt down the SST.

    Replacing the o2 sensor is one of those "replace if it's throwing a code/don't know history of vehicle" parts, at least to me. My guess is the new o2 sensor will clear up that code 5 but if it doesn't there are other options discussed on the site.

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    Re: Oxigen Sensor Special Service Tool. Still available?

    Thank you for responding. I wanted to know if the sensor was good or not. Not so much to save money on it but to properly diagnose the issue because say, I have a good O2, then why I'm I getting code 5? or bad air/gas fumes? but I see what your telling me.. I honestly don't know anything about troubleshooting or maybe I'm just over thinking, that, say, O2 is good or if install a new one but because of other problem causing bad air/gas mixtures then it damages quick then I'm not solving the problem just quick fixing it. But your right it's going to be a PTA to even get close to finding any of them two specially the EFI Checker even dough it would be cool to have a checker, I think it can diagnose many things.

    So $25 bucks?? The cheapest I have seen is $37 for Denso Ebay.
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  20. #17
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    Re: Oxigen Sensor Special Service Tool. Still available?

    Unfortunately, with older vehicles that have these basic types of computers and error codes, the best way that I know of (without a time machine or access to what Toyota techs had back when these were still new) is troubleshooting by process of elimination, AKA throwing parts at it until you fix it. At face value that sounds pretty crappy but there are always parts that are more likely to fail than others, and the FSM will always point you in the right direction. Here is the FSM information for a code 5 error on a 84-85 van:

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    So, if it's not your o2 sensor, the next places to look would be the circuit and, finally, the ECU. Again, these o2 sensors are wear-and-replace-parts, and are subjected to extreme heat and generally terrible conditions. You only realistically get so many years out of these sensors before they give up the ghost and it's time for a new one. A chain breaks at its weakest link, and these typically are it when you get a code like this. Of course, if this turns out not to be the case, then the o2 sensor circuit and the ECU would be your next logical steps.

    And I found the denso sensor on rockauto for $22.79 + shipping. You can easily google a 5% off coupon for rockauto so I don't imagine it costing much more than $25 shipped to your door.

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    Re: Oxigen Sensor Special Service Tool. Still available?

    Thank you, it does give me more clarity and defiantly makes sense, and thanks for the Rockauto tip. I'll be ordering one, and see what happens. Cheers!
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  22. #19
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    Check engine light coming on and off when at highway speeds

    -- 1986 2wd --

    The error code is showing 5 blinks.

    #5 on the list - Oxygen sensor signal. open circuit in oxygen senor signal (only lean indication). 1. Oxygen sensor circuit. 2. oxygen senor. 3. ECU.

    About a year ago my van was sputtering up hills and heavy acceleration. I put in a new O2 senor and it fixed this.

    Currently there are no performance issues, just the check engine light coming on at times when I am going 50mph+

    Could it be the newish 02 sensor again? Is there a way to clean it and what could be causing this?

    Thank you

  23. #20
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    Re: Check engine light coming on and off when at highway speeds

    what brand of O2 sensor did you use? brands other than denso have been known to be unreliable...
    Last edited by boogieman; 12-01-2017 at 05:15 PM.

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