Toyota circuit

Discussion in 'Off-Topic' started by loosewire, Mar 5, 2010.

  1. loosewire

    Thread Starter AAC Fanatic!

    Apr 25, 2008
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    Can any of you guys assume to know,what the ran a way
    curcuit design is. How can electronics cause the promlem.
    Lets start a thread and walk thru it. Let see who makes more sense
    about the conditions. How can fuel be forced to injectors,maybe
    some one has seen some auto scope wave forms.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    That is part of the mystery about Toyota. None of the recalls have so far addressed the "sudden, unexpected acceleration" problem.

    The sticky accelerator mechanism and the floor mat stuff are like the problem I used to have with my pickup truck. In that case, the secondary butterfly would stick open because the pivots got dirty (two barrel carburetor). It was an unexpected continuation of acceleration.

    Toyota has danced around this issue with no satisfactory explanation. The problem sounds like it's in the firmware.
     
  3. loosewire

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    I googled some auto diagrams posted before recall.There was langage about
    the injector being off and increase in rpm's.That the part that maybe some auto guys
    may have some clues. Something about magnetic pital or some thing.Sounded like
    if you cut off one injector the rpms would go up.The run away would have increase
    rpms,for speed.
     
    Last edited: Mar 5, 2010
  4. loosewire

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    I had a with truck dual fuel pumps,It would stop cold,then cool off and run
    until It decided to stop again. I had all the electronic modules changed all the
    best $ 35,000.00 auto scanners from the best companies. A mech with a old sun
    machine, that he didn't need. He was a good mech this ase stuff makes a guy
    understand stuff that he don't want to learn,It helps.But you have to be good mech
    in your head. MY promlem a fracture gasket between the carb and manifold
    sucking air when It got hot fooling the electronic modules to shut down.
     
  5. loosewire

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    Does India make a car,I heard talk about how smart they are.
    When It comes to computers or just phone banks. If you are from
    India set me straight,no harm ment,just asking,you don't learn
    If you don't ask,right.
     
    Last edited: Mar 5, 2010
  6. retched

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    Dec 5, 2009
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    These toyota acceleration problems are possible emf problems resulting from the ground plane not being decoupled from poorly designed systems, or "crosstalk".

    I have not independently researched this, but have heard the drive by wire gas pedal is only using 1 POT, opposed to the standard 3. Typically 3 POTs are used 2 running reversed polarity from the third. These are compared to be sure of proper signaling, and used for redundancy. If one fails, one of the POTs changes polarity to allow usage while displaying the "ENGINE SERVICE" light.

    An oscillation from a leaky alternator can cause the accelerator sensor to confuse the comparator, thinking the driver is requesting more acceleration.
     
  7. loosewire

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    What I would like If you guys walk thru so you can understand your langage better.
    Picture what you said and put into resistant and relays and ground curcuit.
    Don't they use ground for switching on and off. Elimiate some stuff ,If fuel
    is burning,go somewhere esle and back.This could be interesting how the relays and resistors
    work together. Come on guys jump in,it has to be getting air to burn,the coil has to be
    firing for spark to burn fuel. What does the trottle rod do from gas pedal,tigger
    electronics curcuit. Does that leave relays and resistor and grounded capacitors.
    How does it attached to to injectors. Air,spark,fuel,speed.
     
    Last edited: Mar 5, 2010
  8. beenthere

    Retired Moderator

    Apr 20, 2004
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    It's not a mechanical problem. The gas pedal turns a pot like the volume control on a radio. The car computer reads the signal and opens the throttle plate to let in more air and also increases the stroke duration of the injectors to let in more fuel.

    It sounds a lot more like the computer is getting into a mode where it causes the problem when some other inputs are at certain values. It acts like you just stomped the accelerator to the floor.
     
  9. retched

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    The cars use the frame as a return to the (-) battery terminal. If a alternator were to loose a diode, and was then outputting AC, it would swing from + to - and put voltage on the "ground" or the car frame. Now the POT on the accelerator is now getting voltage from the ground, changing the potential. so to the comparator, 0v is idle and 5v is floored. Not touching the gas pedal, the ECM is reading 0v on the line. but when there is accidentally voltage on ground, the ECM is now reading more than 0v and thinking the driver is pushing the gas pedal.
     
  10. loosewire

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    So maybe you can explain better that I when you have pos,you have to less pos
    _+ _+_+ + which is neg. you have more pos , Do you understand. Every one has to
    understand this concept when you have pos,you create less pos,which is neg.
    For electron theory you have to to understand this. Say it better some one..
    Explain how you can have pos voltage on ground.
     
    Last edited: Mar 5, 2010
  11. retched

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    If you take the positive cable from the battery and press it to the frame, or if you hook jumper cables up backwards, it floods the ground plane with positive voltage.

    loosewire:
    Yeah, using ground potential references can get weird. So 0v ground and 5v positive is the same as 370v ground and 375v positive It is still only 5v differential. So with normal logic circuits, 0v is 'low' and 5v is 'high' but you could just as easily use 57v for 'low' and 62v for 'high'
     
  12. loosewire

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    If you have 6 volts positive,5.999 + - .0001 is going to be less positive
    than 6 volts,althought It a postive voltage. To understand this is needed
    as you discover how curcuits work.When you first come across this in a book
    you need to understand some curcuits.
     
  13. shortbus

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    Up until around 1955-1956 ALL American cars where positive ground. After that some British cars were still positive ground.
     
  14. shortbus

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    It sounds to me like Toyota may have brought "LUCAS, prince of darkness" out of retirement to design their electronics.
     
  15. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
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    I wasn't familiar with the "Lucas, prince of darkness" reference but a quick search on the internet kept me entertained for a few minutes!
     
  16. Duane P Wetick

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    Apr 23, 2009
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    My 1966 Austin Healey 3000 Mk II had a positive ground electrical system. The only problem I ever had with it was when the speedo power line accidently abraded itself to the chassis (+) and blew a fuse. Otherwise, I never had an electrical problem with the car.

    Cheers, DPW [ Follow the Money.]
     
  17. loosewire

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    You guys are missing the point or you don't won't to post about the subject
    of pos having a less than pos effect neg on curcuit. One subject may be
    baising by signal effect on voltage. Can some one enlight me on this subject.
    This effect is not in many discussions because of the dificult nature
    of trouble shooting. Its hard to explain.
     
    Last edited: Mar 6, 2010
  18. loosewire

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    So the pot could be intermittant,since it don't do it all the time.
    Maybe the resistor wiper get a build up of carbon and changes valve,
    or get glazed over,a bad connection at zero and go to 5 at the wrong time.
     
  19. retched

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    I guess they are all possibilities.. I still think it may be a crosstalk problem.
     
  20. t06afre

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    The "drive by wire" concept is not new. I have the first standard production car fitted with such system in my garage. It is an 1989 model. This system had never given me any problem. I guess it is a case of a bad design, and the problem is somewhere in the link between the pedal unit and the EML unit.
     
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