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P1780 won't shift out of first gear

Discussion in '3rd Gen 4Runners (1996-2002)' started by alohaimmatt, Nov 7, 2021.

  1. Nov 7, 2021 at 6:00 PM
    #1
    alohaimmatt

    alohaimmatt [OP] New Member

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    Hi all,

    I've had my 2000 Limited Auto for about 5 months now. Yesterday I took it to go shooting in the bush, I filled up on gas and noticed my dash fuel level was only reading half full. I did a bit of off-roading to get to our shooting spot for the first time since owning the truck. Afterwards when I left and got back on the highway I noticed that even when in Drive my reverse bulb was turned on.

    I pulled over to the side of the road and turned the truck off and on again. Once I did this the truck was stuck in 1st gear. I drove it back ~150km in 1st gear keeping the RPMs around 4,000.

    I scanned for codes and got a P1780. Clearing the codes did nothing as they immediately came back. I disconnected the battery for 10 minutes, re-connected it and the CEL went away. However the truck would still stay in 1st gear.

    I read through this forum post below, where the dash printed circuit board was replaced. I just removed my cluster and tried to drive the truck with no cluster, same issue no shifting. I took apart the PCB and it looked okay nothing super obviously wrong. I did notice this one spot however, notice how the connection does not go into the white area. All others (see to the right) do, this position is for the reverse light. Coincidence?

    [​IMG]

    I inspected the Neutral Safety Switch, the connection seemed fine. There was a good amount of dielectric grease which I cleaned up but nothing changed. I attempted to remove the NSS itself however after disconnecting the 21mm nut and washer I struggled to pry it off so I just left it on. I have ordered a new NSS from RockAuto which should arrive this Friday, hopefully I'll have the old one off by then.

    I did also read through this forum post below, however my speedometer continues to work so I don't think it's the VSS. The car has a good ATF level, the previous owner did install an aftermarket navigation unit. They also put in LED head lights, the DRLs are always on no matter the position on the indicator.

    Any ideas on what to check next? Get a used cluster from a wrecker and pop it in? Wait for the new NSS? Thanks.
     
  2. Nov 8, 2021 at 9:34 AM
    #2
    negusm

    negusm New Member

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    What does the factory service manual say? (if anything)

    I don't have mine handy to check.

    This code appears to be specific to the vehicle and to know what it really is telling you, I imagine it's in the FSM or perhaps something can be found in AllData. Which means you may need the help of a mechanic.
     
  3. Nov 8, 2021 at 9:39 AM
    #3
    alohaimmatt

    alohaimmatt [OP] New Member

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    I do not have a FSM. I forgot to mention when I did try to disconnect the NSS the instrument cluster I wiggled it around but was unable to remove it. When I started the truck up again I did have different lights appearing, the reverse stayed on but when doing into 2 the bulb did not illuminate until I went into L then back up.

    I think I just need to wiggle it around a bit and try to get it set properly. Would make sense that off-roading loosened it and messed up the connection. But we'll see.
     
  4. Nov 8, 2021 at 4:20 PM
    #4
    alohaimmatt

    alohaimmatt [OP] New Member

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    Wiggled the NSS around, it did not change any of the lights on the dash. Decided to pack everything up and drop off the truck at Toyota this weekend as it's going to start snowing.
    Will update later when/if it gets resolved with the issue.
     
  5. Nov 9, 2021 at 9:13 AM
    #5
    negusm

    negusm New Member

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    Please let us know what they find. If you do plan on working on the car, the FSM is invaluable. If you hunt the net, you may find it for your year. Ebay sellers sell PDFs for $10 sometimes.
     
  6. Nov 10, 2021 at 7:48 AM
    #6
    alohaimmatt

    alohaimmatt [OP] New Member

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    Found a copy of the FSM online, here's a link below to the blurb about servicing the NSS. Will check voltages later today and go from there.

    https://imgur.com/a/8gV4bIf
     
  7. Nov 12, 2021 at 1:38 PM
    #7
    alohaimmatt

    alohaimmatt [OP] New Member

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    Update, I read the voltages on the ECU harness I got 0v all around in every position. I had ordered a NSS off of RockAuto preemptively, so I did not bother to check for continuity on the NSS harness. Just replaced the NSS, still same problem.
    Truck always thinks it's in reverse, still throws a P1780 code. As per the manual next steps are to replace the harness and the ECU. Going to check around locally to see if anyone has some parts I can get before ordering these up.
     
  8. Nov 22, 2021 at 8:13 PM
    #8
    alohaimmatt

    alohaimmatt [OP] New Member

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    Some more details. When I replaced the NSS with a new one from RockAuto the car threw the same P1780 CEL, as well as a few others. I cleared it, the P1780 persisted, cleared it again and it still came back.
    Today I when to the dealership and explained it, they were able to resolve the issue and the truck is fine again. The techs notes read as,

    > Checked with tech stream and found code P1780. Inspected the neutral safety switch and cleared code. Took test drive with vehicle. Shifting is okay and dtc dtc did not come back. Please monitor it.

    Everything seems good again, I've only put maybe 20km on the truck, but we'll go from there. Not sure why the codes went away when Toyota cleared them and not for me?
     
  9. Nov 22, 2021 at 8:54 PM
    #9
    SR5 Limited

    SR5 Limited New Member

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    Great! You know when it’s cold and you first start driving it will “ride” out first gear. I guess it needs to warm up or something.
     
  10. Nov 23, 2021 at 11:04 AM
    #10
    alohaimmatt

    alohaimmatt [OP] New Member

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    Drove to the office today and got maybe 50km on it. Everything seems good to go, cold starts shift fine and everything is back to normal. Really confused why the dealership clearing codes got them actually removed but using my scan tool didn't?

    Hopefully this will help someone else in the future!
     
  11. Nov 24, 2021 at 11:58 AM
    #11
    PhantomTweak

    PhantomTweak New Member

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    OREGON
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    None. Bone Stock. EXCEPT: Brushguard, tow hitch, both welded to the frame. It's good to have friends and a fully equipped garage!
    If I were to guess, and I am, I would say that the dealership's scan tool is a much more advanced model than you have, with functions that are only available to an "official" Toyota scan tool. Probably has many functions specific to Toyota vehicles.

    It would also cost a great deal more than the one you have, if you were thinking of getting one. Toyota supplies the super-duper advanced version to it's dealerships. You may not even be able to get one for yourself.

    If you used your scan tool to clear the codes, it might have been better to pull the EFI fuse for more than 30 seconds, or the battery negative lead for more than 2 minutes. Why the difference? The air bag system has a 90 second "memory", and if you plug the battery negative lead back on after less than 90 seconds, it might do something interesting to the airbag system. Like set it off, due to the surge in power available when you reconnect the battery negative lead. I'm not saying it WOULD, but I would be afraid it MIGHT.
    That's enough for me to be extra cautious. I'm a chicken about stuff like that, though.

    Does that help?
    Pat☺
     

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