Question about 1999 Chevrolet Silverado 1500

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Just replaced the throotle body,idle sensor,air sensor,now truck wont shift into higher gears just revs,lower gears seem alright

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  • lawndon2 Oct 02, 2010


  • lawndon2 Oct 03, 2010




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Does it come out of first gear? This is an important question.

Posted on Oct 02, 2010

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  • danny mcwilliams
    danny mcwilliams Oct 03, 2010

    1) Was the transmission upshifting O.K. before the Throttle Body and sensor changes?
    2) When you say just revs in higher gears (with an automatic there are only three speeds with an overdrive (4th))--are you saying that it goes in a neutral state? Is there any engagement after 2nd upshift, does it actually shift to a third that has no pull/slips?
    3) This is an automatic I presume, 4l60E?
    4) I again am assuming this is not a Manual 5 speed. Correct?
    We will figure this out once I can see what you are actually saying, we are getting there!

  • lawndon2 Oct 03, 2010

    the trannie shifts good coming out of the first two gears but does go into a nuetral state at third and overdrive

  • danny mcwilliams
    danny mcwilliams Oct 03, 2010

    Usually when an automatic transmission loses a "gear" i.e. no foward, or shifts from first to third, or loses 2nd and third, it is a internal transmission problem due to the fact that the 1)clutches are burned out for that particular gear or there is one of a myriad of internal issues that can cause this.

    What I need you to do is to get into the truck start it, put it in low. Drive off in low gear, get up to 3,000 rpm (or so) and upshift manually once to 2nd. Get up to 3000 rpm (or so) in second and upshift manually to third. This will tell us if a manual upshift forces the transmission to go into third or not.
    (Getting up to 3000 rpm in 2nd may take you past the speed limit, if it does, just upshift at the speed limit to see if it goes manually into third.) Don't break the law if possible. :)

    Did you say reverse worked OK?

    Also try to drive it normal and let it upshift until it hits the neutral state as you say, and then down shift one gear at a time and let me know when it goes back into gear (does it go back in in second or first? This is what I am looking for). ***Remember that 4th or overdrive is a function of the torque converter "locking" up, so its slip speed decreases (by manipulating the fluid flow through the converter halves internally) and esentially causes less of a differential (difference) between the crankshaft out put speed and the input shaft speed of the tranny. Thus letting you feel like there is a 4th gear, (overdrive).

    Anyway, I digress, try this and write me back...this is our first test.


  • danny mcwilliams
    danny mcwilliams Oct 03, 2010

    I asked before, did it work OK before you changed the throttle body? Your original statement kes it look like it did...anyway, clutch pak for third gear or throttle valve (for downshifting is stuck). Because you can feather it in third, and without me seeing it, this would be my diagnosis.

    Obviously a trans person would have to drive it, but I am afraid I am on track--the only thing that bothers me is that third gear clutches are not known for burning up, third gear has the least amount of torque and actual abuse than lets say 2nd or Reverse.

    Only other thing is to disconnet the downshift device and se if that works.

    See a qualified trans guy I think we tried everything.

  • danny mcwilliams
    danny mcwilliams Oct 03, 2010

    Can U get a hold of a Tech II, it will help you pinpoint the answer.



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