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Help needed. 4L80E transmission will not shift into Overdrive

This is a discussion on Help needed. 4L80E transmission will not shift into Overdrive within the Technical / Maintenance forums, part of the General Discussion category; Need some advice and input on my 97 K2500 Chevy, the transmission will not shift into overdrive. Haven't had any ...

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    Help needed. 4L80E transmission will not shift into Overdrive


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    Need some advice and input on my 97 K2500 Chevy, the transmission will not shift into overdrive. Haven't had any other issues with the trans, just noticed that trans will not go into overdrive. Checked fluid and it was a little low on dipstick, so I added a bit to bring it up to full mark, still no OD.

    I don't know for sure when this started, as we had a blizzard last week and most driving was under 40 mph, so I didn't notice anything out of the ordinary until the weather cleared and I was back on the road @ 55 mph. Trans is not even trying to shift, just goes into 3rd and stays there when shifter is in OD. Any thoughts on what is going on here? Hoping for a simple fix and not having to rebuild transmission (or replace).

    Truck has about 165,000 miles on it, and trans fluid was changed around 50K, so I know it is due for another change according to manual. Will changing the fluid/filter fix this, or is the problem in the electronic shift in the transmission? Any ideas or info will be greatly appreciated, as if the truck quits I am on foot!

  2. #2
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    Re: Help needed. 4L80E transmission will not shift into Overdrive

    have it scanned see what comes up if no codes most likley the 4th clutches are gone. if 4th is all you have lost I would say the latter. also check to see if 4th gear is being commanded if it is then again looks like a failure in the overdrive circuit/clutches. your in Illinois you may want to hit up vince bielanski formrly of FLT he is doing his own thing now on the side very good guy and good freind. if interested i could have him call you if you need that kinda help

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    Re: Help needed. 4L80E transmission will not shift into Overdrive

    transbuilderguy,

    How do I go about having the transmission scanned for codes? Can auto parts stores do this, or do I need a GM dealer or trans shop?

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    Re: Help needed. 4L80E transmission will not shift into Overdrive

    you would be better off taking it to a repuatble trans shop.

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    Re: Help needed. 4L80E transmission will not shift into Overdrive

    Okay, first call tomorrow is a transmission shop.

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    Re: Help needed. 4L80E transmission will not shift into Overdrive

    Okay, a little update:

    Called two trans shops today, one number disconnected and the other said tech guy would call back and hasn't yet. Will try again tomorrow. Looking under truck around trans I have some ATF fluid leaking, not sure if it is from the trans or T-case. T-case has always leaked a little so not certain where fluid is from, but fluid is on shift linkage on drivers side of trans near some electrical connectors. So far no real progress.

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    Re: Help needed. 4L80E transmission will not shift into Overdrive

    There's an over-flow tube sticking down from the trans at that area. Maybe you just added a bit too much fluid? No problem, as it will come out the over-flow tube.

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    Re: Help needed. 4L80E transmission will not shift into Overdrive

    Update:

    Took the truck to the trans shop and put it on scanner. Didn't show any codes but the tech scanned it another way and it has a bad shift solenoid? in the trans( I can't remember exactly what he called it). He is going to price it and get back to me, the fix involves dropping the pan to replace, along with fluid and filter change. Tech said it is okay to drive and the truck will only get less mpg the way it is.

    Waiting to see what this will cost, if the trans has to be rebuilt the price tag is $2500. OUCH!!

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    Re: Help needed. 4L80E transmission will not shift into Overdrive

    Call your local chevy dealer and get it done there. been there done that.IMHO

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    Re: Help needed. 4L80E transmission will not shift into Overdrive

    Quote Originally Posted by mj2562 View Post
    Call your local chevy dealer and get it done there. been there done that.IMHO
    Could you elaborate please?? Are you referring to replacing the solenoid or rebuilding the trans??

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    Re: Help needed. 4L80E transmission will not shift into Overdrive

    Did you check the fuse? If I understand the 4l60e, pulling the fuse will force the trans into 3rd. Maybe the 4l80e is the same.
    Last edited by slug; 02-08-2011 at 06:43 PM.

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    Re: Help needed. 4L80E transmission will not shift into Overdrive

    failsfe for a 4l80e is 2nd gear 4l60e is 3rd

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    Re: Help needed. 4L80E transmission will not shift into Overdrive

    I registered to follow this thread, as I have the same problem with 1993 K2500 Suburban

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    Re: Help needed. 4L80E transmission will not shift into Overdrive

    Hello fellow chevy owners. I just bought a 95 3/4 ton with a 4l8oe trans that will not shift into 4th/OD.

    Did anyone ever figure out what the most common cause of this problem is? I replaced the speed sensor and it shifts into all the other gears just fine.

    The guy I bought it from said that it shifted fine when he got it. Then started acting up not going into forth. He said he would unhook the battery from time to time and then it would shift fine for a time then go back to not shifting into 4th. This leads me to believe it is something stupid rather than a bad trans.

    Should I take it to the chevy garage and have them "scan" it? I would hate to have that done then have them tell me they have no clue or would a tranny shop be better?
    Last edited by tbones32; 05-05-2011 at 11:09 AM.

 

 

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