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: 700r4 still screwed up! Lock up problem '88 k-5 REVISITED

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by backlash, Jan 20, 2001.

  1. backlash

    backlash 1/2 ton status

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    : 700r4 still screwed up! Lock up problem \'88 k-5 REVISITED

    Hey Guys,

    Thanks for all the help on this in the past ... still not working. Just reread the original thread and am not sure where to go from here.

    Replaced the Throttle Position Sensor which had no effect. According to the shop manual under "no converter clutch release"

    1.solenoid ... external ground (works when cold but not when warm doubt this is it)

    2. converter ... internal damage (replaced twice with no effect)

    3. oil pump assembly ...converter clutch apply valve stuck (Conceivable that this is sticking as it gets hot)

    ... anybody know where this is located? Can't find it anywhere in this book. Is it something I can/ should replace with the TCC solenoid while in the pan?

    Seems to me that the TCC solenoid may stop working when hot?

    .

    For those that don't know ... had my tranny rebuilt after returning many times now the TCC will not disengage when warm. Works perfectly for 15-20 minutes at highway speed then quits.

    Any suggestions would be appreciated. Going on 3 months of torture.

    Anyone want a truck?
     
  2. yeild2me

    yeild2me 1/2 ton status

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    Re: : 700r4 still screwed up! Lock up problem \'88 k-5 REVISITED

    according to my popular mechanics cd manuals, there were several problems like this-it has a diagram of the front pump assembly and that is where the the valve is located.
    if you want more info, here is TSB- i wish i could send it to you, but i dont know how. it is reading it off the disk, and i cant move it to my hard drive-

    Technical Service Bulletin

    trasmission- all GM lock-up
    bulletin- #046
    subject- lock-up
    application- GM
    date- april 91

    LOCK-UP Problems-----this tsb covers no lock-up and no lock-up release.

    but to abswer your question it is in the front pump housing

    AIRBORNE!!
     
  3. redbeast

    redbeast Registered Member

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    Re: : 700r4 still screwed up! Lock up problem \'88 k-5 REVISITED

    Been reading your post, been scratching my head, few questions for you. has the rebuild
    shop checked the temp switch on the valve body ? the 93 4l60 has this switch on the vbody
    ( small can looking with 2 wires) on the 4l60E it,s part of the pressure manifold ( black thin 2''x 4''x1/4 thk)
    mounted on the bottom the valve body. Its used to not let it lock up until it reaches a certin temp for faster engine warm ups. its possibly thats its breaking down when it gets hot. Outher than the PCM it's the only thing I can think of that will effect the lockup electricaly. The pump has the converter valve that turns the converter off an on when the solinod tells it too. 4l60s to 93 had shuddle valves in the valve body,93 to 94 did a way with these and started using the PCM to control L/up with the help of thr tv cable. The 94 on did away with the tv and governer and started letting the PCM do it all...Hope this helps..
     
  4. yeild2me

    yeild2me 1/2 ton status

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    Re: : 700r4 still screwed up! Lock up problem \'88 k-5 REVISITED

    i agree. that is pretty much online with the trouble shooting tree on these discs. it lists if it un-locks when the brake is depressed, shorts on the solenoid wire, clutch valve sticking, etc. the only problem is that after each thing it list a test reference to use with the shop manual. with no shop manual they are useless..
    BTW-does it unlock when the brake is depressed hot or cold?


    AIRBORNE!!
     
  5. redbeast

    redbeast Registered Member

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    Re: : 700r4 still screwed up! Lock up problem \'88 k-5 REVISITED

    It should not lock up tell it gets to opreating temp if has the temp switch. What are using for a manual ? CD
    or a haynes ,chilton etc. Ive got some ATSG manuals that use when I rebuld them but they are at the shop
    list what what you info system say's maybe I can fill in the blanks...
     
  6. redbeast

    redbeast Registered Member

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    Re: : 700r4 still screwed up! Lock up problem \'88 k-5 REVISITED

    It should not lock up tell it gets to opreating temp if has the temp switch. Brake peddle deprssed or not. What are using for a manual ? CD
    or a haynes ,chilton etc. Ive got some ATSG manuals that use when I rebuld them but they are at the shop
    list what what you info system say's maybe I can fill in the blanks...
     
  7. backlash

    backlash 1/2 ton status

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    Re: : 700r4 still screwed up! Lock up problem \'88 k-5 REVISITED

    Thanks,

    Yes, it does unlock hot or cold when depressing the brake
     
  8. yeild2me

    yeild2me 1/2 ton status

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    Re: : 700r4 still screwed up! Lock up problem \'88 k-5 REVISITED

    these are popular mechanics automotive software cds. i has all of the service bulletins and this is where im getting this info. for this prob, it starts off asking if it releases if the brake is depressed- ill start there-- bare with me on this-
    does tcc release when brake is depressed? y or n (ill do the y's first)
    y-check for short to ground on D wire (see test #5)
    short-check solenoid
    no short-computer system prob (see test 13)

    n-check brake switch-
    bad-replace
    ok-check solenoid(test 9)
    solenoid bad-replace
    solenoid good-check for stuck l/up valve (see test 11)
    l/up valve stuck-correct stuck valve and retest
    l/up valve not stuck-block l/up valve in unlocked position.
    still no release-torque converter or pump propblem
    no lock up-signal oil proble(see test 12)

    there you go____ kinda weird writing it this way but maybe you can get the jest of what its saying
    BTW-these discs or for 88-89 vehicles so it should be correct if the trans is the stock one>>>


    AIRBORNE!!
     
  9. redbeast

    redbeast Registered Member

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    Re: : 700r4 still screwed up! Lock up problem \'88 k-5 REVISITED

    Ok i follow your train of thought all the way to the part were it says to block the valve in the open position. Not real sure how they do that. Ive blocked the valve closed with check ball trick to make them locup no matter what the PCM tells it to.. The trans thats is in my blazer is not PCM controled at all.I puta switch in line to turn the l/p when I want it to,but mine is a 85 non efi, I thinks yyou can still do that on yours but Im not sure witch wire to place the switch, have to look at the wiring diag to tell... By the way when the solinod has been removed the L/up valve is directly above it held in place by a snap ring. Can be removed from the bottom kinda tricky geting it back in but it can be done..
     
  10. turbo

    turbo 1/2 ton status

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    Re: : 700r4 still screwed up! Lock up problem \'88 k-5 REVISITED

    The piston can get stuck via some little piece of crud but then converter is always locked and you cannot sit stopped in drive with the engine running.

    The little solenoid could fail open if shorted out or lost ball but I cannot envision any way the solenoid could fail in a way to cause you symptoms.
     
  11. backlash

    backlash 1/2 ton status

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    Re: : 700r4 still screwed up! Lock up problem \'88 k-5 REVISITED

    Robert,

    This is not an intermittent problem ... occurs every time I drive highway speed. AND always releases when brake pedal depressed(hot or cold).

    Does this disc explain the "YES" tests?

    #5 What is the "D" wire. Again not intermittent ... works fine when cold, then messes up when hot. Therefore, doubt it's a short ... unless it's that solenoid.

    If I drive it to make it hot, then try to do the test, it's liable to cool off enough to stop acting up ( while draining the fliud and removing the pan) ... possibly the same senario for the ECM. I've been unable to get someone else to drive it long enough to make it act up... too busy(their excuse and more)! Can't keep taking days off work!

    What is envolved with replacing that selenoid ... looks like it's just inside the pan?

    What is the check for the ECM? Test #13.

    Thanks,

    Bob
     
  12. backlash

    backlash 1/2 ton status

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    Re: : 700r4 still screwed up! Lock up problem \'88 k-5 REVISITED

    Just thinking that the clearance there is so minute that as it heats up and expands ... it siezes.
     
  13. turbo

    turbo 1/2 ton status

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    Re: : 700r4 still screwed up! Lock up problem \'88 k-5 REVISITED

    SINCE THE BRAKE PEDAL UNLOCK WORKS VIA THE SOLENOID THERE IS NO WAY CHANGING THE SOLENOID WILL HELP.
    All pushing brake pedal does is open a switch thus cutting off 12 volts to the solenoid.
    The partial throttle unlock works the same way cutting 12 volts to solenoid either by TPS or a vacuum switch depending on model.

    The solenoid is just a little electro magnetic coil that when activated moves steel ball to close a passage thus applying fluid pressure to the lockup piston.

    You problem has to be electric before the solenoid or the brake relaese could not operate.

    If you want to rig it just get one of the old vacuum manifold switches used in early to mid eighties and wire it into wire to solenoid and whenever you apply enough throttle for the manifold vacuum to drop the TC will unlock and for about $8 you will be done with it. Just don't tear into the tranny cause no way the prob is inside.
     
  14. yeild2me

    yeild2me 1/2 ton status

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    Re: : 700r4 still screwed up! Lock up problem \'88 k-5 REVISITED

    i did some deeper digging on the discs, and found a wiring diagram..turbo is right, if it releases w/ the brake, then the solenoid is fine.FYI-the solenoid should be greater than 20 ohms- if its less it can cause ecm failure... i am going to send you two pics of the diagram...its kind crapy because im using a web cam and sending you the pics...as far as the test numbers are concerned-i havent a clue, i guess you need the manuals for them...

    AIRBORNE!!
     

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