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Truck rolls in park

Z71 CC LB

By Z71 CC LB
in Troubleshooting & Recalls

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Z71 CC LB Enthusiast

Z71 CC LB

Posted
Posted

I was sitting I my truck with it idling on a decent incline with the truck in park and suddenly I was rolling back wards. It happen twice in the same instance as I was waiting on a driveway to pick up my son. At first I didn't know what was happening but hit the brake and stopped, then lifted my foot and a few seconds later I was rolling down the driveway again. I also noticed a complete drop out or total loss of power when making a hard right attempting to merge with traffic. I have felt the drop out a few times all in the same conditions, hard turn and hard acceleration. The loss of power does not sound or feel like the tranny though. I don't feel it slipping or hear the engine rev when it happens. The rolling started yesterday the hesitation has happen a few times but definitely a few times yesterday. The truck is a few months old with about 3500 miles it. Any ideas?

brwk Enthusiast

brwk

Posted
Posted

WOW, that's scary....get it to a dealer or shop!!!!!

pm26 Senior Enthusiast

pm26

Posted
Posted

There is a pawl in the transmission which should engage when the transmission is placed in Park. Maybe yours does not engage properly? Either way, get it fixed ASAP. This is dangerous.

  • Like 1
Doug64 Enthusiast

Doug64

Posted
Posted

I would definitely get it to your dealer asap. Keep us posted.

  • 5 months later...
austingta Enthusiast

austingta

Posted
Posted

The shifting is really electronic now, even though the shifter feels connected. Since in flat-tow mode the park position is disabled, it may be related to that. It's a dealer issue no matter what .

  • 4 years later...
Paul Ricci New Member

Paul Ricci

Posted
Posted

Hmmmm?  So I have a new 2019 3500HD Denali with the 6.6L Duramax Diesel motor and Allison transmission.  Same issue of rolling backwards.   I got home the other night about a week and half ago from grocery shopping.  Parked the truck on my inclined driveway to unload groceries.  I KNOW it was in park, and the motor was turned off....as I had the keys in my pocket.  I opened the back door, brought a load of groceries in the house and set them down, came back out and the truck was in the street!  Thinking that "maybe" I didn't get the truck in park properly (even though I an engineer with a graduate business degree, in my mid 50s, and NOT insane), I got in the truck, started it, and pulled it back to the original parking location in my driveway.  I check at least 3 times to ensure the stick shift was in fact in PARK.  It WAS!  So I turn off the motor, get out, shut the door and grab some more groceries from the back seat.  As I walk away from the truck I hear a "click"/"pop" sound, and I turn to see the truck rolling backwards into the street again!!!!  It was "lurching" backwards as it appeared some mechanism was attempting to engage to stop it.  It was not a smooth roll.  Eventually, that something engaged, and the truck stopped......in the street which is flatter.   I had something similar the first month I bought the truck in May of 2019, where it only rolled back about 1 or 2 feet.  For that, I though maybe I just parked it in the wrong spot, not pulling in as far as I normally do.  Those of you who park cars in a driveway location know that probably park within 1 inch of your normal location.    Anyway......each time this happened, it was very cold outside - perhaps 20 degrees F, or colder.  This latest time, I had just driven the truck, so the tranny and engine were warm when it happened.  The dealer (Alpine GMC in Denver area) just looked at it, and could find any issues or bulletins.    I would encourage others to write and document.......cause someone is going to get killed with this issue!  Had there been a kid behind the parked truck playing in the day, or had someone been walking on the sidewalk, they would have been rolled over!  The Service tech at the dealer informed me when I called in that just had another guy with the same issue in the shop.  But his truck was the 1500 and gas motor with a different transmission.  There WAS a service bulletin on his, but doesn't apply to my model.  In the meantime, I will be consistently using my parking break!  Eventually, someone will be killed and lawsuit filed.  GM needs to resolve this!

redwngr Senior Enthusiast

redwngr

Posted
Posted

Imho, if parking on a slope that is steep enough for the vehicle to roll in neutral, then the parking brake should be used.

This is to prevent damage to the parking pawl, but also to prevent it from getting stuck in park. 

 

The 'hill start assist' system will prevent it from rolling -- but only for a few seconds. 

Reading the original post I wondered if maybe it wasn't in park, or pawl was broken/not engaged and it rolled when HSA released. 

 

HSA scenario doesn't explain what happened with Pau's 3500/Allison.  

 

 

I assume the thread OP won't ever follow-up with the outcome.  Hasn't visited since Sept 2016.

 

 

 

 

  • Like 1
Colossus Senior Enthusiast

Colossus

Posted
Posted

What I do-  I apply the parking brake while the vehicle is still in drive, foot on the brake pedal. then shift it into N and take my foot off of the brake pedal so that the load then shifts onto the parking brake, THEN put the vehicle into park.  Make sure the parking brake is being serviced every time you have the regular brakes serviced. 

  • Like 1
  • 2 weeks later...
Paul Ricci New Member

Paul Ricci

Posted
Posted

Re: the comments above.   Well...yes.  It goes without saying that if the transmission is in Park, and it rolls backwards now 4 different times, I would obviously start using the emergency brake on regular basis when it is parked on a slope.

To be clear also......I am 150% certain that the Truck was firmly in Park each and every time!  The dealer explained to me that I am not the only one who has complained of this issue......although there is no bulletin yet from GM for this model.  They did look at the transmission, but were unable to identify an issue.  Trust me when I tell you.......this transmission HAS AN ISSUE!

At some point, someone is going to get killed......some kid playing behind a parked truck, someone walking their dog on a sidewalk when the thing rolls back.  Maybe not my truck, but there is evidence this is not the only instance of the issue.  Somewhere in America, someone is going to get killed......and THEN GM might decide to do something about this and look into it more.

  • 2 weeks later...
Zadd New Member

Zadd

Posted
Posted

This just happened to me today . 
My driveway is on a slop and I put it in park , set the parking brake and started to get out of the truck as it started to roll back . Only way I could get it to stay put was to put it in 4 high . It has done this twice in the last 5 years but is random when it does this . Drove it later that day and had no issues with it rolling down my driveway. 

gearheadesw Senior Enthusiast

gearheadesw

Posted
Posted

This is scary ****** right here. My truck has never done it, '17 2500hd,  but just the thought of coming out of a job site or restaurant, and finding the truck all piled up against a car in the parking lot. Try explaining that one to the insurance company.

  • 2 weeks later...
DieselD New Member

DieselD

Posted
Posted

I have. 2011 Sierra 1500. This happened twice today. Parked in my driveway came back to find it had rolled back. Thought I was losing my mind. I pulled it back up and set the emergency brake. Checked 2 hours later and it had rolled back again. This time I have sand bags behind the wheel. Guess I'm heading to the dealer in the am. Assuming no one has heard of a fix?

  • 2 years later...
sliding silverado New Member

sliding silverado

Posted
Posted (edited)

this is happening to me several times now. 2021 silverado The truck is rolling in the park, AND the truck has rolled back on a light incline , going to the dealer tomorrow , I made a post with video of attached 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited by sliding silverado
  • Sad 1
diyer2 Senior Enthusiast

diyer2

Posted
Posted

I find it hard to believe that it rolls with the PB set, unless it's not set properly or theirs a problem with the PB. I live in the mountains and flat surfaces are rare. My 12 has drum rear brakes with old style cables for the PB. I have parked on slopes with my boat, 4K pounds and other trailers weighing more and NEVER had my truck roll. It will sometimes move a little until the rear drums lock up. 

I say user error.

 

 

  • Thanks 1
Silverado4x4 Senior Enthusiast

Silverado4x4

Posted
Posted
38 minutes ago, diyer2 said:

I find it hard to believe that it rolls with the PB set, unless it's not set properly or theirs a problem with the PB. I live in the mountains and flat surfaces are rare. My 12 has drum rear brakes with old style cables for the PB. I have parked on slopes with my boat, 4K pounds and other trailers weighing more and NEVER had my truck roll. It will sometimes move a little until the rear drums lock up. 

I say user error.

 

 

Iam with ya on that, that right rear wheel was sliding on the ice and no PB was applied if it was free wheeling like in neutral that truck would have kept rolling into the street.

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