8 speed acts like it's in neutral when shifted out of park

[Donnyb313]

My trucks latest issue.. 1 year old, 5500 miles and having transmission problems. 

 

Went to pull my truck forward in my driveway which is slightly sloped. Started truck, shifted into drive, let off the brake and it rolled back like it was in neutral. The transmission was not engaged into gear. Hit the gas a little and it just revved like in neutral. 

 

I thought maybe the linkage was messed up, so I put it into L1 and it still rolled and felt like it was in neutral. 

 

Then I went from L1 to reverse and it wouldn't engage reverse. I put it back into drive and revved it beyond 2000rpm, then it roughly slammed into gear and chirped the tires. 

 

Same issue when I went out to leave today, revved it up and it slammed into gear again. It's not the linkage. 

 

Once again I'm wishing I would've kept my 2015 2500hd. Rear end pinion seal, steering column replacement and now this. I worried to keep this truck beyond warranty period. Off to the dealer it goes. 

[swathdiver]

You're supposed to have Hill Start Assist, no?  Check your owner's manual.

[Donnyb313]

10 hours ago, swathdiver said:

You're supposed to have Hill Start Assist, no?  Check your owner's manual.

Yes, I know what hill start assist is and the truck has it.

 

The problem is that it doesn't go into gear. Can't move forward or back and the truck just rolls. Once I revved it above 2000rpm it slammed into gear. 

 

Today it worked fine. Guess I get to wait to see if the problem comes back before I take it in, otherwise they'll just say can't duplicate the problem. 

[swathdiver]

1 hour ago, Donnyb313 said:

Yes, I know what hill start assist is and the truck has it.

 

The problem is that it doesn't go into gear. Can't move forward or back and the truck just rolls. Once I revved it above 2000rpm it slammed into gear. 

 

Today it worked fine. Guess I get to wait to see if the problem comes back before I take it in, otherwise they'll just say can't duplicate the problem. 

Ok, that sounds like a pump problem to me, or a solenoid being slow to operate.  If those T1s can be diagnosed with GDS2 software, I would be recording data to play back at the dealership.  They use GDS2 software to work on these trucks.

 

Now you can use an MDI2 adapter with the software (GDS2) on a laptop or a VXDIAG NANO with the software on a laptop or tablet.  Do a data record from the transmission module and if it does it, play it back for the technicians.  Should have thrown a code (internally) but of course I'm diagnosing from my arm chair a long ways away.  Keep us posted regardless, I do not recall the issue you're having on the forums before.

[B.R.67]

On 3/14/2020 at 4:02 AM, Donnyb313 said:

My trucks latest issue.. 1 year old, 5500 miles and having transmission problems. 

 

Went to pull my truck forward in my driveway which is slightly sloped. Started truck, shifted into drive, let off the brake and it rolled back like it was in neutral. The transmission was not engaged into gear. Hit the gas a little and it just revved like in neutral. 

 

I thought maybe the linkage was messed up, so I put it into L1 and it still rolled and felt like it was in neutral. 

 

Then I went from L1 to reverse and it wouldn't engage reverse. I put it back into drive and revved it beyond 2000rpm, then it roughly slammed into gear and chirped the tires. 

 

Same issue when I went out to leave today, revved it up and it slammed into gear again. It's not the linkage. 

 

Once again I'm wishing I would've kept my 2015 2500hd. Rear end pinion seal, steering column replacement and now this. I worried to keep this truck beyond warranty period. Off to the dealer it goes. 

I have a 2019 RST 8 speed. Two months ago my transmission did the very same thing it had 5000 miles on it at the time. It slammed so hard into gear it chirped the tires and lunged forward.it has only done this one time  but this transmission has the hesitation after backing up and going forward and after this incident has seem to pickup a vibration and shutter. I had the dealer look at it and they said it has the new synthetic transmission fluid in it and they could not get it to duplicate anything issues.  I do think  it has something to do with the pump and fluid. I live in upper Michigan very cold winters and it seems this may attribute  to my issues. I had a 2016 with a 6 speed and once  the transmission went through the learning process it was a good transmission. This 8 speed has  more strange behavioral issues the more miles it gets. I will never have another 8 speed.

[Donnyb313]

Thanks for the replies. My truck hasn't done it again since those 2 times. So I haven't taken it to the dealer yet. It was about 25 degrees out that day. But I never had any other issues throughout winter. Makes a guy wonder if the trans will hold up beyond the warranty period. I'm going to bring it in, so it's at least documented. 

 

My transmission always seems to start out from a complete stop in 2nd gear. Unless you really hit the gas, then it will drop into first. I don't like it and I'm wondering if that's normal for the 8 speed. I have 35's so I think that's why I notice it so much. With regular size tires I don't think it would be an issue. 

[bigdoug42]

My own experience is when you shift from reverse to drive let it sit in neutral for one to two seconds, I don't know why but it seems to help the transmission's overall performance.