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4l80e lost all gears

This is a discussion on 4l80e lost all gears within the Technical / Maintenance forums, part of the General Discussion category; Posting for a buddy, but from my understanding the truck is a 92 gmc sierra sl with the 4l80e. The ...

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    4l80e lost all gears


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    Posting for a buddy, but from my understanding the truck is a 92 gmc sierra sl with the 4l80e. The other day the truck lost all forward gears and reverse; and needed to be towed. I'm unsure of the circumstances surrounding the lose of the gears i don't know if the truck was being driven as it happened or he started the truck and was unable to move it. Regardless, i was able to pull some codes from the truck and got codes 24, 68, 85, 86, 87. I also checked the transmission fuse just to rule that out and it was still good. What could possibly be causing this issue? Does it sound like a possible electrical issue or a mechanical/hydraulic issue? any help would be greatly appreciated...thanks
    Last edited by slsierra; 04-29-2013 at 01:49 AM.

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    Registered User 1998454's Avatar
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    Re: 4l80e lost all gears

    Is the truck a 4x4? It's not rare to lose all gears and can be caused by a number of things, but park is 100% mechanical and rarely lost. Even if park was gone you should still have gears. Is it possible the transfer case has jumped to neutral, or broken? If it's 2wd i'd look at a possible broken output shaft.

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    Re: 4l80e lost all gears

    I believe the truck is a 4x4...After contacting the owner, i guess there was a little miscommunication. The truck does in fact have and hold in park, but has no movement in forward gears or reverse
    Last edited by slsierra; 04-27-2013 at 03:12 PM.

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    Re: 4l80e lost all gears

    A week or so prior to this happening, there was an issue with the transfer case being shifted into neutral. Is it possible that this has something to do with the transfer case seeing as the transmission had no signs of it going out? Shifted smooth, went into gear easy, no slipping.

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    Chevy2500HD 6.0 Thomas6284's Avatar
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    99% sure the trans in that year truck is the 700R4 but could be that one % I'm wrong. But if it doesn't have park I'm thinking broken output shaft.
    Last edited by Thomas6284; 04-27-2013 at 04:30 PM.

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    GMC RULZZ NEUMANNZZ's Avatar
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    Re: 4l80e lost all gears

    if its a 3/4 ton it will have the 4l80e.might be a bad torque convertor or pump. check fluid level off. then run engine if fluid level doesnt go down either bad tc or pump.
    O2 GMC RCSB 4.8L V8 AUTO 3.73's
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    Re: 4l80e lost all gears

    If it "lost park", and also "lost" other gears, odds are about 99.99999999999% AGAINST it being anything to do with the transmission.

    Drive shaft & transfer case, would be the prime suspects. Esp the TC.

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    Re: 4l80e lost all gears

    The car has park, just some miscommunication on my end. Is it possible that a faulty vehicle speed sensor could be causing these issues seeing as the truck keeps throwing a code 24
    Last edited by slsierra; 04-29-2013 at 02:50 AM.

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    Re: 4l80e lost all gears

    Just thought I'd throw in my 2 cents... Or 5 cents now I guess... But if the truck has been defaulting to 3rd gear occasionally along with the speed and tach not registering... There's a pretty good chance it's the ignition switch harness failing on you... I have a 95 chevy that had that exact issue... A friend who read the codes said that all the errors were to do with the transmission malfunctioning, if that helps

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    NO ROOF RACK NEEDED kemble's Avatar
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    Re: 4l80e lost all gears

    Pull one of the transmission cooler lines and start the truck. See if any fluid is pumping. Then report back.
    SOLD: 04 z71, 3200 circle D, longtubes, Corsa sport, TBG 4l60e, 93 BB tune, 4500K HIDS, and other aftermarket stuff.

    Quote Originally Posted by 03SMURF View Post
    you have the meanest sounding 5.3 I have ever heard in person

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    Registered User 1998454's Avatar
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    Re: 4l80e lost all gears

    The speed sensor wouldn't cause loss of all gears. Until the truck moves, the sensor isn't communicating with the computer.
    Quote Originally Posted by slsierra View Post
    The car has park, just some miscommunication on my end. Is it possible that a faulty vehicle speed sensor could be causing these issues seeing as the truck keeps throwing a code 24

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    Re: 4l80e lost all gears

    Quote Originally Posted by JBanger View Post
    Just thought I'd throw in my 2 cents... Or 5 cents now I guess... But if the truck has been defaulting to 3rd gear occasionally along with the speed and tach not registering... There's a pretty good chance it's the ignition switch harness failing on you... I have a 95 chevy that had that exact issue... A friend who read the codes said that all the errors were to do with the transmission malfunctioning, if that helps
    Haven't had a chance to look at the truck yet, but its funny you mention that the speedometer and tach not working because prior to this happening the speedometer and tach wouldn't function properly at certain times. How would i go about testing the ignition switch harness?

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    Re: 4l80e lost all gears

    bump

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    NO ROOF RACK NEEDED kemble's Avatar
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    Re: 4l80e lost all gears

    I stated it before, Pull a cooler line and make sure fluid is being pumped.
    SOLD: 04 z71, 3200 circle D, longtubes, Corsa sport, TBG 4l60e, 93 BB tune, 4500K HIDS, and other aftermarket stuff.

    Quote Originally Posted by 03SMURF View Post
    you have the meanest sounding 5.3 I have ever heard in person

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    Re: 4l80e lost all gears

    will do, i just want to know how to check the ignition switch harness if the pump checks out

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    Re: 4l80e lost all gears

    Had a chance to check out the truck, pulled a tranny cooler line and it was pumping fluid strong....what should i look into now?

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    Registered User 1998454's Avatar
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    Re: 4l80e lost all gears

    Are all the plugs at the trans in good shape and fully connected? No fuses blown? You can also remove the shift linkage and unbolt the selector switch plate from the side of the trans, move the link by hand and verify it is dropping into all the detents as you move from one gear to the next. While the plate is off you can also remove the 1/8th pipe plug and install a pressure gauge. While running, the pressure should jump quickly when the engine is revved quickly. Beyond this, you will be needing to verify computer output voltage is going to the solenoids.

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    Re: 4l80e lost all gears

    All plugs appear to be in good shape and are connected firmly. The trans fuse in the fuse box was still good. How would i go about checking if computer output voltage is going to the solenoids

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    Re: 4l80e lost all gears

    O2 GMC RCSB 4.8L V8 AUTO 3.73's
    rebuilt/beefed up 4L60E(at 43,000miles)
    Matching Ninja 500r


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    Registered User dave89iroc's Avatar
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    Have you tryed all shifter positions? Cause you can unplug the wiring harness, and still have manual 2 and reverse iirc

    Sent from my EVO 4g
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    2000 Silverado 6.0 4L80E 2wd
    *RIP*1994 Z71 SCLB 355, Dart Heads, 10.5:1 CR, PM rods, CC XR270HR

 

 
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