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4l80 e trans problem

Discussion in 'Chevy Trucks' started by Sharper Edge, Feb 14, 2008.

  1. I went out to the garage today to take my 1991 gmc 3500 4x4 up to yhe car wash and no reverse??? checked the fluid it was fine. Decided I would take it up for the wash drive was still working. On the way there I notice no overdrive?? I have the 4L80 E trans Does this sound like a mechanical problem or electrical? THANKS
  2. Redneck

    Redneck Senior Member
    Messages: 187

    Sounds like its all over, time for a new trans
  3. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    If it lost reverse and forward at the same time it's not likely a hard parts failure.

    Sounds like the "A" shift solenoid is stuck or defective. It's located in the valve body and can be changed without removing the trans.

    Get a scanner on the truck first though before just replacing it. You can view the A solenoid activity on to see what you come up with. Could also be a wiring problem to the A solenoid.
  4. Just lost reverse. 1,2,3 still work and shift fine just no overdrive
  5. Duncan90si

    Duncan90si Senior Member
    Messages: 602

    The same exact thing happened to mine a few months ago, Except I lost 3rd too. Trans was junk. It had a cracked drum and a bad center support.
  6. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Sorry Sharp, typed "forward" instead of "overdrive"...diagnosis is the same though. :)
  7. KeeblerBP

    KeeblerBP Member
    Messages: 35

    I had the exact same problem with my 4L80E in my last truck. It was a metal band that broke that runs reverse and overdrive. I heard a bang when mine went out. The dealer told me I could replace just the band for about $700 or rebuild the whole tranny for about $1500. I spent the $1500 thinking that with my luck something else would go out a few months later and I would have to spend it anyway.
  8. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    The rear band will definitely make it lose reverse, but isn't applied for overdrive. So I doubt thats the problem with Sharp's truck (if it sends debris though the trans it could clog a passage or solenoid though).

    To lose reverse and OD at the same time almost has to be electrical or solenoid related.

    Only way to help pinpoint it future is to get it on a scanner and check it.
  9. bassfishn1

    bassfishn1 Member
    from ct.
    Messages: 30

    same thing happened to mine, lost reverse first, then all the others, except first, good thing my tranny guy was only 2 miles away

    he told me the whole wiring harness and related solenoids were fried
  10. Thanks guys.. Getting it scanned this morning. I will let you know what it is.
  11. Detroitdan

    Detroitdan PlowSite.com Addict
    Messages: 1,937

    I lost OD in mine, tranny shop told me tranny was junk. I replaced TCC solenoid, shift solenoids, ect switch, speed sensors, harness seal and finally rebuilt the valve body with a Sonnax kit. All it was is the afl valve (controls lockup) wears in it's bore, creating a hydraulic pressure leak so TCC won't work. With the kit you remove the valve, ream and sleeve the bore and reassemble. Tranny is working perfectly now, all told I spent less than $400 trying to fix it, it really only needed about $250 of that to fix with the kit. Far cheaper than the $2200 tranny shop wanted to replace my "junk" transmission.
  12. Detroitdan

    Detroitdan PlowSite.com Addict
    Messages: 1,937

    BTW, keep us posted with your codes. If we can't help you here, I can hook you up with a guy who used to teach rebuilding 4L80Es to Motor T mechanics in the military. If he can't figure it out, then it isn't a 4L80E.
  13. snowcan

    snowcan Member
    Messages: 52

    When the reverse band busts, you usually feel it, almost like sledge hammer hitting your rear bumper, very common for the reverse band to fail on the 4L80E. Before you rebuild, check for the price on brand new, I found there wasn't much difference and the new one had a 3 year/60 000 km warranty.....good luck.
  14. Had to get trans re built. on 2-18-08 it is now 12-2-2008 1345 miles on trans and I just lost 3rd and overdrive. any help? It is still under waaranty but would like to know what you might think it is before I take it up. 1345 miles not real sure about the rebuild being a good one..
  15. dirtmandan2

    dirtmandan2 Senior Member
    Messages: 275

    my 4l80 also went out last winter, never made a dound just lost reverse... that and when i tried to go forward it fealt like i had a foot on the brake... 2250$ later I got it back... builder said no warranties on a plow truck... hope you have some luck with yours...
  16. Have the warrahty just want to know why it would go bad with 1345 miles on it..
  17. dirtmandan2

    dirtmandan2 Senior Member
    Messages: 275

    Im by far not a tranny guy, but i would say that whoever rebuilt it missed something...
  18. aeronutt

    aeronutt Senior Member
    Messages: 262

    Warranty = "not your problem". Let the rebuilder fix his mistake. If you want to understand the inner workings, not just get it fixed then I suggest buying the shop manual and reading it cover-to-cover. You'll learn far more than you will by sorting through an internet forum where clueless people (like myself) toss out a lot of "maybe this", and "maybe that" guesses. I'm not saying the forum isn't helpful, just that it's not a perfect data source.
  19. Pulled a code today off PCM of 81 says solenoid b short or open. going to change trans guy said not under warranty was not relaced with rebuild. Is this a easy job looks like just pull the pan and replace? Should I replace the filter with only 1345 miles on it or is that just a waste of money?
  20. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    If your replacing the B solenoid yes of course you will have to drop the pan....but you'll also have to drop the entire valve body assembly in order to remove the retaining pin that holds the solenoid in place.

    The B solenoid is likely the issue as to why you have no overdrive...and not uncommon, but wouldn't cause it to lose reverse. When they lose reverse its due to a broken hard component, such as the rear band or band anchor pin for example.

    So basically you've got a bigger issue than just a non operating B solenoid. :cry: