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Engine Check Light?

Discussion in '80-Series Tech' started by Rogue, Apr 26, 2003.

  1. Rogue

    Rogue

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    While driving last night the Engine Check Light came on. My truck is a 94. How do I go about diagnosing the problem?
     
  2. landtoy80

    landtoy80

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    Rogue, If you have a service manual you can check the code stored on your computer as it stores many problem that your 80 might have. Get a piece of wire and find the little black box next to the firewall on passanger side that says diagnosis. Connect the wire from E1 to TE1 and turn the key to on (don't start). Count the flashing check engine light. Example and my bet that it is,code 71 EGR. 7 flashes then 1 flash = 71. If there is more than 1 code there will be a gap bewteen them. A steady flash = no problem stored. It could be O2 sensor, if so it is a recall and Toyota will replace the first time.
    kurt
     
  3. Rogue

    Rogue

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    Kurt,

    You are the man. Okay, it flashes 7 times, then once. Is that the code for the O2 sensors? I think that is how I understood your post, but I just want to make sure. Thanks.
     
  4. landtoy80

    landtoy80

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  5. cruiserdan

    cruiserdan SupportingVendor Emeritus Supporting Vendor Moderator

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    Rogue,
    a 71 is EGR system malfunction.

    The O2 codes are 21 and 28

    PM your vin to me and I will see if the O2 sensors have been replaced under the SSC. It won't help the 71 but at least you will know....................... :beer:


    Dan
     
  6. Rogue

    Rogue

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    So what does the 71 mean, and what must I do to fix it?
     
  7. landtoy80

    landtoy80

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    You can test the EGR. There is several parts to test. You will need a service manual. My EGR code Check Engine light comes on and off. I am going to take the EGR and intake assembly apart and clean it and test the parts under the intake. Still waiting for part. Pull the EFI fuse in the fuse box under the hood and wait 30 sec. and put it back in. This will clear the code. THe light might not come on for a while or will come on and off or stay on. Mine did all. If you want to fix it your self get a Toyota Service Manual or pay the dealer lots of $$$$$$$$$$$$$$$$$$$$$$$$$$$ to fix.
    kurt
     
  8. Beowulf

    Beowulf

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    Rogue & Kurt,

    I'll go out on a limb here, at least a little out on the limb.

    I struggled with a P0401 EGR insufficient (OBD-II) for about 16 months. I cleaned the EGR valve. 1 month fix. I cleaned the EGR modulator. No fix. I replaced the EGR modulator. No fix. I replaced the EGR valve. 4 month fix. I cleaned the EGR pipes. No fix.

    Several people had posted that this code was resolved, usually by their mechanic, with the replacement of the VSV for EGR. It's under the intake manifold but can be accessed without removing the intake. I'll post limited instructions if you decide to go this route. I had my mechanic replace the VSV and the code has not come back for about 5 months. Ask for the pn because the dealer will have trouble identifying which is the correct part. There are 2 VSV's under the intake and their book doesn't say which is the VSV for EGR.

    -B-
     
  9. landtoy80

    landtoy80

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    When I have the intake chamber off I will test and clean the VSV and if posable I will remount it where it can be replaced easyer. It cant be to hard to extend the wire and hose. Is there any reason why I couldn't move it?

    What size vaccum hose is/are there that I should replace? I might as well replace any hose that is hard to get to while in there.
    kurt
     
  10. Beowulf

    Beowulf

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    Kurt,

    >> and clean the VSV <<

    There isn't much, if anything, that you can clean on the VSV. Maybe the electrical contacts but they are pretty well protected anyway. The hoses are the small ones; Dan will know the ID. I can go out and measure the ID of the nipple on the VSV if you want. It looks like 2mm or so.

    Test per the FSM. It's basically an electronic gizmo so I wouldn't replace it unless it fails the tests. It's also spendy; about $90 list I think.

    -B-
     
  11. landtoy80

    landtoy80

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    You would think that if it was the VSV, as it is electrical, that the CE light would be on all the time. My light come on then off every once in a while. Unless there is a short in the wire?
    kurt
     
  12. Beowulf

    Beowulf

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    Kurt,
    My VSV failure began as an intermittent failure and, over several months, became a hard failure.
    -B-
     
  13. Cruiserdrew

    Cruiserdrew SILVER Star

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    Here is the part number for that VSV. Mine died at 75k miles. Since replacement 1 year ago, the EGR code has not returned.

    Part # 90910-12079 Valve, Vacuum switch.

    I watched the Toyota Tech change it out and he didn't pull off the intake manifold. Good luck.
     
  14. Junk

    Junk

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    Hey B. I've had that same dang error code now for close to a year :eek:. Once every few weeks I plug in the OBDII just to make sure there's no other code. If you had to replace the VSV again, would you do it yourself or take it back? I pulled the hose and stuck a screw in it :slap: for the last 6 mos, but would like to get it fixed. Was waiting for someone to post the fix on the 80's list, but lost interest in the thread since no one ever seemed to get it fixed.

    Soooooooooooooooo, in other words, should I call Hocker, get the part and do it myself, or see[glow=red,2,300]THE DEALER[/glow]:dunno:
     
  15. Beowulf

    Beowulf

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    Junk,
    I would do the repair myself if I were to do it again.

    I had a local shop do the work since I wasn't certain it was the VSV for EGR and I was fed up with throwing parts at the darn thing. I had confidence this guy (Toyota Master Mechanic) would isolate the problem and get it permanently fixed. Total cost was 2 hrs labor plus the part. About $200 total. This included his time to set up and use the Toyota tester and to isolate the problem. I filled him in on the things that I had already done to try fixing the problem. The time also included drive testing to be sure the problem was fixed (P0401 is a 2-trip logic.)  He had left off another hose during the testing and it failed the first drive test.

    I talked with him about 15 minutes when I picked it up. He described the procedure that he used. He did NOT remove the intake.

    My guess is that a pro can do this in less than 1 hour. 2 or 3 for me. From under the truck (he had a lift of course) you take about 3' of ratchet extension and remove a bolt holding the VSV  bracket (see 1st pic below) to the under side of the intake. From under the bonnet you remove a support bracket on the intake. Then you can squeeze a hand in and remove the hoses, taking care to remember which goes where because you can't see them very well. There is an electrical connector that must be removed. The pics will help you be sure you are removing the correct part; you can tell by feel once you know what it looks like.

    Here is a picture of the VSV. It is sitting on pliars with black grips to prop it up for the picture.
    [​IMG]

    You will notice the bracket has a little lip on it. This goes in a mating bracket under the intake. Seeing it will help envision the removal.

    Here is another pic of the VSV (sorry for the fuzzy images)

    [​IMG]

    After removal, you can test the VSV using the procedure in the FSM. Mine failed the resistance test and was definitely bad. Installation is the reverse.

    Let me know if you need anything else.

    -B-
     
  16. landtoy80

    landtoy80

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    Junk, I was going to disable the EGR. I asked the LCML about this and got a responce that I will damage my pistons. I don't know why as the AU 1FZ doesn't have an EGR or cat.
    kurt
     
  17. Beowulf

    Beowulf

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    Kurt,
    I'm pretty sure we had this discussion before; maybe it was on SOR. The pertinent information from the below referenced link is:

    EGR Effect on Emissions & Driveability
    Too little EGR flow may cause detonation and IM240 emissions failure for excessive NOx. Because EGR tends to reduce the volatility of the air/fuel charge, loss of EGR typically causes detonation to occur. If EGR is commanded but doesn't flow (restricted passage in manifold, nonfunctional valve, etc.) severe detonation will occur.


    OZ spec 1FZ-FE's and other non-EGR countries use a different ECU.

    See this for a write-up of Toyota EGR systems.
    http://www.autoshop101.com/forms/h61.pdf

    I drove my truck for a LONG time with a P0401. Like Junk, I would reset it every so often but it would come back on the 2nd trip. I would also check for other codes, fearing my MIL light might be masking another more critical problem.  I didn't hear any detonation. I couldn't detect any difference in performance or fuel economy.  

    That Check Engine light was driving me crazy.

    -B-
     
  18. Junk

    Junk

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    Thanks B - big time. Will ring up Hocker and as soon as I don't gotta worry about any nicks will get to it. Heck, I even wore 4 pairs of latex gloves to change my oil on Sat :D - dang last person was the dealer during a check on the new engine and he frickin tightened it up so much......... :slap:

    Thanks and will get to it soon - hopefully. :beer:
     
  19. Gumby

    Gumby Supamod Staff Member s-Moderator

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    Hi. My name is Gumby and i have EGR low flow.

    This is the PO401 support group isn't it? :D

    I've had my MIL on for about a year when I got tired of all the usual fixes. I was going to pull the intake to do the PHH. Maybe i'll try to jam my chubby, scarred hands in there and do them both with the intake on. I figure if I fix the VSV and the D light, the heater hose will blow the next day.
     
  20. Junk

    Junk

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    Gumby - sounds like a great extra credit project for one of your classes - kids have skinny arms :D