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4L60 transmission issue

Discussion in 'GM Powertrain' started by mug23, May 28, 2009.

  1. mug23

    mug23 New Member

    Hello,

    I have a 95 1500 Suburban with 4L60 tranny. It seems to be having some issues where when I put it in OD to drive normal pace, it quickly shifts into the highest gear right after the initial pick up. When I try and press the gas pedal to the floor, the tranny still will not shift to the next lower gear so the truck can have a better pick up speed.

    I have already replaced the filter and trans fluid few months ago and I may have over fill it, not 100% sure. Could this be the case that's causing it? Does anyone here may have experienced this issue before?

    Your help will be greatly appreciated.
  2. Mean_Green_95

    Mean_Green_95 Epic Member 5+ Years 1000 Posts

    being overfilled could possibly cause that. My friend bought a Jeep Grand Cherokee and the trans was overfilled. He said it wasn't shifting properly and when it did shift it was hard. We sucked out some of the fluid and he said that that fixed the transmission problem totally.
  3. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    Your problem sounds like a stuck TV valve. Look for your TV cable which goes from the throttle body to the transmission. Once you find the cable you want to try to free the valve. Hold the engine at a steady 2000 RPM and then rapidly pull and release the TV cable in and out as fast as you can about 20 times. This in many cases will free up your TV valve. The TV valve is the valve you need to downshift the transmission when you floor the gas pedal.

    The transmission being over full should have no effect on kick down but you should make sure it's not over full as this can start a fire and burn up your truck.
  4. mug23

    mug23 New Member

    Thank all for your reply. I will check on that.

    What exactly is a TV valve?
    Last edited: May 29, 2009
  5. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    The TV valve tells the transmission where your foot is on the gas pedal. When you floor it the TV valve downshifts the trans to a lower gear.
  6. mug23

    mug23 New Member

    Hummm, I can't see to find the cable. The cable i see is attached with the throttle cable. The thing is, when I put in 4H instead of 2H on the transfer case, the truck shifts normal. Once I place it back to 2H, it still shift very very quickly to the next higher gear and it feels like I'm riding in OD all the time.

    I'm stuck...

    Thanks,
  7. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    If you don't have a cable then you have a 4L60E. Now that you mention it shifts OK in 4 hi but not 2 hi you may have a wiring problem where your computer thinks you are in 4WD Low range when you are in 2 WD. This problem is not an uncommon one. Have you inspected your transfer case connectors? I would unplug and check for corrosion at all the connectors and inspect your wiring harness for abrasions.
  8. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    I forgot to add one important thing. When your truck is up shifting quickly in 2WD Hi if you were to watch your truck data on a scanner you would probably see the computer is displaying 4WD Low when it is actually in high range. A bad 4WD Low switch can cause this as well as a wiring or connector problem.
  9. mug23

    mug23 New Member

    Thank you very much for your replies. I believe you maybe correct as the mechanical is working correctly and I'm pretty sure there's nothing wrong with the transmission itself.

    I will check the wiring to see. I have a 500 mile trip coming up with towing my race car and I need to get this fix. If not, I guess I will have to do the shifting myself.

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