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Chevy Silverado and GMC Sierra Transmission Problems



  • I have a 2005 Sierra with similar though not exact symptoms. The dealer informed me that the error codes suggest that the issue is the encoder motor, which is a device (mounted on the front differential) that shifts your front differential in and out of 4WD. It responds when you push the Auto 2WD 4WD and 4WDL buttons on your dash. My encoder motor no longer responds to my button pushing (i.e., will not shift in and out of 4WD), though up to recently it responded intermittently. An encoder motor is more than $700 installed at the dealership. I found a place online where you can get a remanufactured one with a lifetime guarantee for just $299. I have been told that it is a simple installation for anyone who can turn a wrench and plug in a lamp. I'm going to order it today.
  • friend i really appricate the info except it doesn't explaine all of allison problems:new tranny/torque converter 3 new tranny lines new starter 8 new injectors and 16 new push rods. this all happened at the dealer. i didn't know a 45k truck was supposed to self destruct at 29k miles. maybe fred flintstone wasn't so stupid after all !! still driving my rental pos
  • tedp1tedp1 Posts: 2
    Sorry for the delay. Thank you for the help. I'll let him know and see what he says.
  • svroomsvroom Posts: 1
    When I floor the accelerator for passing gear, the transmission does not upshift when it should. The engine will wind to 4500 RPM and the transmission is in low gear or second. The transmission works fine normally.

    no DTCs for the transmission. :confuse:
  • I have A 01 silverado 4.8L great truck!
    but every so often starting from A stop it will
    seem to hesitate in the tranny. almost like the
    the brakes stick.Any one have A problem like
  • I have a 93 Silverado 204,000 on it, has always ran great except a couple of weeks ago I noticed that when I take off The trans shifts way to quick into the overdrive gear which bogs down the truck. It's fine when I manually shift progressive through the gears. Any solutions?
  • fiberguyfiberguy Posts: 1
    Looking for anyone else that has an 8.1 with the 6 Speed manual---Mine has developed a rattle near the base of the shifter, it only can be heard under acceleration or load. It happens in all gears dealer can not tell me if this is normal since they work on very few of these transmissions.

    I am hoping maybe another owner can help.

  • grumphygrumphy Posts: 6
    I have an 04 1500 silverado with the 4.8 motor.
    The tranny slips only when hot and at low rpm when shifting from first to second.
    on fast acelration it shifts fine.this only happens from first to second and only when hot on low aceration.trans was flushed but no change.
    thanks for any help
  • bigt442bigt442 Posts: 6
    I have a 1997 Silverado 4l60-E transmission with no reverse, I rebuilt the trans and now the truck is locked down and will not move even in neutral. It shifts in every other gear and will move forward. You can tell it shifts into reverse but acts like the brake is on, what could the problem be? any clues? This makes the 4th one I have rebuilt and this is the first time with this problem. :confuse:

  • fordfan_17fordfan_17 Posts: 175
    ok drop the pan and put the 3 8mm bolts where they are supposed to be i know exactly what happenned. as i made this mistake myself quite a few years ago all 3 8mm bolts go 1 to left of epc solenoid and 2 even with wire connector what has happened is you one of these bolts in the wrong place if you need a picture lemme know ill get it for you
  • fordfan_17fordfan_17 Posts: 175
    have you had the filter changed ???? some shops will use silicon on the pangasket blocking the 2-4 exhaust hole which will cause servo problems....if there is silicon on your pan gasket get it off 2-4 band failure will happen if you dont
  • bigt442bigt442 Posts: 6
    I have the pan off and will move the bolts as you say. If you have a picture that would be great. Thanks for the quick responce.
  • fordfan_17fordfan_17 Posts: 175
    5 minutes check my photo album the location for the 3 bolts are in yellow paint
  • bigt442bigt442 Posts: 6
    Thank you very much!!!! :shades:
  • bigt442bigt442 Posts: 6
    Fordfan 17
    Just wanted to let you know it worked. You are the man and thanks so much for the help. I will pay more attention the next time.

  • fordfan_17fordfan_17 Posts: 175
    np at all... hope i helped you give me some ranking :) lol j/k
  • i have a oo sierra with 5.3. its slipping in reverse like its not totally engaging i can hear it go into gear but wont seem to grab. this is the third transmission i have put in and really cant afford to do it again. any suggestions
  • I wrote before but never got any feedback so I thought I'd try again. My truck occassionally shifts really hard into 2nd gear. It seems like it this mostly happens before it is warmed up but can happen at any time. Downshifting seems fine. I've had it in to a tranni guy who sent me to GMC to have the computer reset. The GMC guy took off the pan, found no filings or anything in the oil could not visually see any problems.

    Also, when I bought this truck, there was no manual--it has electronic 4x4. I change into 4H up to about 60 kph. 4L I change in Neutral. Is this correct? Also, my friend changed into 4x4 with the steering turned hard (I nearly freaked)--did she damage U-joints or anything?

    Finally, does anything know where I could find a manual and/or a keyless remote (the truck did not have those either!) :blush:

    Thanks Ali
  • Does anyone know why this is happening....once my Sliverado 1500 4x4 has been sitting on an incline not running and I go to start it and put it into reverse the truck dies. I have to coast in neutural until I get to flat land. Once on flat land I can go forward. Any ideas?
  • diton908diton908 Posts: 7
    how do you bleed the clutch is it just like bleeding brakes or what the bleed is on the slave cyl i replaced the line between the master cyl and the slave cyl cant get the clutch to feel right and it pulls when the clutch is all the way depress i know that isnt right and i think i have air in the line but cant seem to get it all out if you could help thank you

    95 chevy 2500 5.7 #50 V8 4x4 5 Speed
  • KCRamKCRam Mt. Arlington NJPosts: 3,516
    The incline is likely draining the torque converter. Two things will help: set the parking brake before you shift into Park when you're parking the truck on that incline. Then when you start it, shift into Neutral with the parking brake still engaged to release the stress on the park pawl and help get fluid flowing through the system sooner.

    kcram - Pickups Host
  • wclementwclement Posts: 1
    how do i remove the broken clutch pedal without removing the dashboard ?
  • farenfaren Posts: 2
    I am clueless about mechanics and am out of state with truck problems. It's an '04 GMC 2500HD with about 60K miles. A couple days ago it started shifting "hard" while going through the gears. I took it to the dealership before leaving VA and no codes came up on the diagnostic, said the fluid was a little dirty but nothing else so it would be safe to drive to NC. It drove perfectly fine coming down. But when I tried to leave it shifted much harder while moving through the gears and then the check engine light came on. I had the truck towed to a local GMC dealership (it is under an extended warranty) and when I backed the truck off of the tow truck I looked down and the engine light wasn't on anymore. I put it into gear and drove it around the parking lot and seemed fine but then shifted hard again once or twice.

    What could be the problem? I hate to say it, but I'm a girl and don't want to be taken for a ride by the dealership. Thanks!
  • fordfan_17fordfan_17 Posts: 175
    there are a couple of different transmissions that came with this vehicle 4L80E or Allison 1000 would need to know a little more detail before i can be of any help to you
  • drosenaudrosenau Posts: 2
    I have a 2001 2wd, GMC Sierra, automatic. The button for the tow/haul option is on the end of shifter. This doesn't work but the Tow / haul option comes on by itself sporadically. The indicator light comes on on the dash and I can feel the truck gear down. Any advice before I take it to a mechanic.
  • obyoneobyone Posts: 8,054
    Sounds like a short in the wiring for the switch causing the intermittent engaging of the tow/haul mode.
  • drosenaudrosenau Posts: 2
    Thanks, do recommend any particular vehicle manual to trace the wiring?
  • obyoneobyone Posts: 8,054
    The factory service manual from Helm's is $135.00 plus shipping. You can also get online support via where you are able to subscribe to your specific vehicle and obtain service info and TSBs regarding your truck. I've found that while the manual is good, alldatadiy provides much more accurate data versus those other manuals that you can purchase at Checkers. I think its $14.95 for a years subscription and you are able to print out the schematics that you'll need.
  • hdcoxhdcox Posts: 2
    I have a 1997 chevy 3500 vortec 350. It only has 70,000 miles on it, but reverse has went out. It acts the same as if it were in neutral. All else seems ok. I havent had the filter changed since I bought it at 35,000 miles. It has fluid in it, I even put a can of Gunk trans fix in it. I was considering Lucas tranny fix, please help if you got a fix. I was told by the oil change guy that changing the filter may make it go out altogether. Im lost. Any information would be greatly appreciated.
  • fordfan_17fordfan_17 Posts: 175
    first out changing the filter will not make reverse come back. im sure this is a 4L80E transmission and it has a problem with the reverse band wearing out the front planetary assembly. and i will say this about additives DO NOT USE THEM once you put the chemical into the transmission it does not stop working until you drain both the torque and the trans. in otherwords if you use an additive it will continue to soften the rubber items in the trans till it softens them away.then you have a catastrophic trans failure that will cost much more to repair than it will if you get the problem fixed correctly instead of trying to fix it with a majic potion
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