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Another Check Engine Light Saga

Discussion in '80-Series Tech' started by Jim_M., Jun 10, 2003.

  1. Jim_M.

    Jim_M.

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    I just purchased my first landcruiser a little over a month ago. It's 1997 40th anniversary edition w/ 102000 miles on it. After owning it for 2 weeks my check engine light came on. I had it read by a Toyota dealer here in Salt Lake City. The code was PO401. I had the EGR valve, the VSV valve as well as the temp sensor replaced by the dealer. After getting it back I drove it for a few days and the light came back on. The dealer told me the code was now PO402 (EGR flow excessive). The first thing they did was clean the intake manifold. The light went out and off I went (no charge). Of course, the light came back on a day later and I took it back again.
    They then replaced the new vsv and the vacume switch thinking they were faulty. This didn't make the light go out.
    Their latest advice is to replace the computer at $1400.
    I'm not a whiz mechanic by any stretch ( I do my own brakes, rotors and stuff like that) but something doesn’t seem right w/this. Any advice or info you guys have on resolving the PO402 code or thought s in general would be really appreciated. Thanks in advance.
     
  2. Gumby

    Gumby Supamod Staff Member s-Moderator

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    So far the things I've heard that have worked have been the VSV and the intake clean. I have also heard of the EGR pipe being cleaned, but with no results.
    I starting to think the OBD II programming is just too sensative for the EGR.
    I just ordered my intake gasket kit for the VSV clean/replace and the pesky heater hose. I hope it can be fixed.
     
  3. ParadiseCruiser

    ParadiseCruiser

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    Greetings Jim -

    Welcome to the list.

    &nbsp:Don't feel bad. I have seen so many 97s with this P0401 issue that I am begining to think Gumby is right: We're all trying to fix something that ain't really broke!

    My 97 (40th) spits out P0401s regardless of what I clean, or replace... and has been doing so for 6 months. I still have a few more ideas, but the field is narrowing. Best advice is to stay tunned and see what some of the rest of figure out.

    Cheers, Ron
     
  4. landtank

    landtank SILVER Star

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    I just broke out my manual for this problem and thought I'd throw my .02 in. Acording to the manual after the second 3 minute trip at speeds between 43~56 mph if the EGR temp senser reads a low temp condition it gives a P0401.
    My approach to these types of problems is to divide and conquer. After that second 3 minute trip and the light goes on I'd take an OHM reading between pins E4/19 and E5/9 on the ECM. The reading should be between 188.6 ~ 439.0 k ohms. The plugs should be removed to avoid reading an internal resistance.
    If the reading is correct then the problem lies within the ECM or one of it's supply voltages. Since the senser requires 5vdc and we have a 12vdc system that 5vdc has to be manufactured either in the ECM itself or elsewhere.
    If the reading is wrong I'd then read the Temp senser directly to confirm that the wiring is ok from the ECM to the senser.
    Anyone having this problem and would like help trouble shooting it further I'd be happy to help. Throwing parts at a problem blindly is often expensive and time consuming.

    BTW: E5/9 is the ground side of the senser. Any resistance read between that pin and the frame would be added to the resistance of the senser and give a cold condition.
     
  5. cruiserdan

    cruiserdan SupportingVendor Emeritus Supporting Vendor Moderator

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    Rick,
    Blind parts tossing is an effective way to get the dog fed :G . Your approach is the most sensible one I have yet heard. I see the guys in the shop checking that "manufactured" voltage often for a variety of issues.

    There is one surefire cure. The 93/4's don't do this because they are too stupid :ugh: . So you could take the radiator cap off and drive one of those under it ::) .

    :beer:
     
  6. Beowulf

    Beowulf

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    Jim_M,

    First I want to vehemently agree with Gumby. Something in the later models (maybe *just* the 97's) is set WAYYY to sensitive with the EGR logic.

    However, I am living proof that the P0401 problem can be fixed. Do a search here in the 80s section for plenty of posts on the subject. We won't bore everyone else with the history lesson.

    >> They then replaced the new vsv and the vacume <<
    >> switch thinking they were faulty. <<

    Please take some time and go back through your old repair receipts and pull the part numbers and dates. The above statement is redundant as the VSV *is* the vacuum switch. The reason I want to see part numbers is that there are 2 different VSV's in the same location. My suspicion is that they are replacing the WRONG VSV; they should have replaced the VSV for EGR.

    If it makes you feel any better, there is only 1 remaining part they have not replaced (assuming your information is correct.) The EGR Modulator is part of the EGR system. It's also the easiest to replace and the cheapest. It also has a filter in the top that may need cleaning. Cheap repair if it works. Clean it with compressed air and be sure the coarse side is up when you put it back in the holder. No tools required.

    >> Their latest advice is to replace the computer at $1400.  <<

    Hell would freeze over before I dropped $1,400 for a new computer to fix the EGR codes.  You can buy a cheap box to test and reset the MIL and keep the other $1,200!

    Keep us posted and good luck!
    -B-
     
  7. landtoy80

    landtoy80

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    Jim
    When they cleaned the intake, did they remove it and clean? It is a big job to remove and clean and they did it at no charge??? Or did they just spray something into the intake? Ask them. I had so much build up on my intake that I had to use a pick and lots of carb cleaner to clear it. I have the old 94 computer and only have code 71 EGR. All I did was clean the intake chamber. No more CE light.
    kurt
     
  8. landtank

    landtank SILVER Star

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    C-Dan,
    It's been my practice to first confirm that the error is legitament. Most people fail to realize that it is actually 2 circuits that they are dealing with. The first is the circuit that does the job, in this case recirculating the gas. The other circuit monitors the first circuit for problems.
    An easier solution to turning off the light other than replacing the whole truck would be to place a 400kohm resistor in place of the temp sensor, that way the ECM would always thinks it is the right temp.
     
  9. cruiserdan

    cruiserdan SupportingVendor Emeritus Supporting Vendor Moderator

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    Rick, that would be cheating, but, :givecrap: If it works, it's COOL.
     
  10. landtank

    landtank SILVER Star

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    Dan, a buddy of mine's solution when we were yonger was a 6" philips screw driver through the dashboard. Light never came on again :eek:
     
  11. cruiserdan

    cruiserdan SupportingVendor Emeritus Supporting Vendor Moderator

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  12. Jim_M.

    Jim_M.

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    Thanks for all of your responses....all my receipts and my manual are home right now. I need these to sound somewhat intelligent in here ; )

    I'll post part numbers and a few questions about this when I get home tonight.

    This is a great site. Hopefully, I can actually contribute something someday.
     
  13. Beowulf

    Beowulf

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    Jim_M,

    >> I'll post part numbers and a few questions about this when I get home tonight. <<

    Great, this will help us determine exactly what they replaced.

    >> Hopefully, I can actually contribute something someday. <<

    Didn't someone mention that we'll expect a percentage of that $1,400 you'll save? We generally split it among those that provide helpful information. It's all sent to Beowulf@PayPal.com then we divvy it up from there. :G

    -B-
     
  14. landtank

    landtank SILVER Star

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    Dan, the actual situation was on an older Chevy stationwagon. It had this habit of turning on the HOT light only after the car had completely boiled over. On the third incident my buddy grabbed the nearest weapon and drove it through the face of the dashboard straight into the bulb's heart! I almost pissed myself at the tirade.
     
  15. cruiserdan

    cruiserdan SupportingVendor Emeritus Supporting Vendor Moderator

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    Rick,

    Um, WOW :killtard: I guess I was just curious. I wondered if say a Snap-on would be more effective than say a Matco or maybe a Mac, or Craftsman. I thought that the ones in the popcorn tub for .99 might deflect or something :dunno:
     
  16. landtank

    landtank SILVER Star

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    Dan, definately no Playschool brand was used, most likely Snapon! :G

    Jim I'm glad to help however I'm a diagnose/troubleshoot kind of guy. This technique is usually saved as a last resort for some reason because people look for that quick fix from someone else's experience. I'll watch the thread and jump in if I have something to offer.
     
  17. Jim_M.

    Jim_M.

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    Beowulf:
    The parts and numbers for the first EGR job are:
    25620-66011 Valve Assay, EGR
    25627-66010 Gaskets, EGR Valve
    89412-60020 Sensors, EGR Gas TE
    90910-12079 Valves, Vacuum Switch

    Nine days later it was back and they cleaned out the intake system.
    Landtoy80, no they did not remove the intake when they cleaned it.

    Five days later it was back and that’s when they replaced 90910-12079 Valve, Vacuum Switch, thinking it was faulty. My apologies for the redundancy confusion. That was my fault.
    Where is the EGR modulator located relative to the EGR system? I have access to a compressor tonight and would like to blow the filter out.
    I have no problem sharing the money that I save from you rappin' with you guys…as long as it goes towards cheap beer and expensive tools.

    Thanks again.
     
  18. Beowulf

    Beowulf

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    Jiim_M,

    >> cheap beer and expensive tools. <<

    Is there anything else worth spending money on?  :G

    >> 90910-12079 Valves, Vacuum Switch <<
    That is the correct part for the VSV for EGR.

    It isn't clear whether or not the EGR MIL returned following the replacement of this part. Several people, including me, had the problem fixed after this part was replaced. However, our problem was a persistent P0401, not the P0401 then a P0402.

    (Note, you don't have to remove the EGR modulator to remove and clean the filter)

    The EGR modulator is to the right of the EGR valve. If you're standing in front of the truck looking toward the rear, it is toward the back of the engine just to the left of the valve cover around the #5 plug. It can best be described as a small flying saucer shaped thingy.  It snaps in and has 3 hoses attached. Be sure you know which hose goes where, remove the hoses and snap it out. No tools required. The filter is on top, underneath the colored cap (colors changed between original and replacements.)

    The filter is a white round thing about 1/8" thick and about the size of a silver dollar. It has a coarse side and a smooth side. IIRC, the coarse side goes up. Just be sure to note which side goes up when you remove it. It may be black with carbon buildup. Use compressed air to blow from the smooth side to the coarse side.

    New ones are around $60 list. C-Dan will know the p/n and the actual list price. He's also a good source for parts and only makes enough profit to feed his dog each day. Call late in the day and your price will be cheapest if he sold something earlier in the day. If not, you'll feed the dog by yourself.  :G

    -B-
     
  19. Jim_M.

    Jim_M.

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    Well I pulled the EGR Modulator and took a look at the filter...clean as a whistle. Interestingly enough it was in the opposite way of how you described it. The filter consisted of two separate layers: one course and one smooth. The course side was down and the smooth side was up. I’m assuming that the port inside the modulator draws air in. If that’s the case, it seems logical that the course side should really be up and the smooth side down. I’m sure that’s not the reason my light is on but it seemed strange. I put it back the way it was.

    Am I crazy for driving this thing around w/ the light on? It runs great. My only fear is something else goes and the light being on will mask that.
     
  20. Beowulf

    Beowulf

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    Jim_M,
    I was recalling the orientation of the filter from memory so maybe I had it backwards. I'll check the FSM this evening.

    The MIL light being on and masking another problem was the thing that bugged me the most. FWIW, you probably are not doing any harm and there are several of us that have driven with the P0401 code and the MIL on for long periods.

    The tests for the EGR modulator are pretty simple. If you don't have the FSM then let me know and I'll describe the tests or fax you the pages.

    -B-