jQuery not supported.



Transmission seems to drop into neutral when off gas

Transmission seems to drop into neutral when off gas

Postby Rich235 [OP] » Nov 07 2019, 6:06am

Hi everyone,

New to this forum and hopefully all the knowledge here can put my mind at ease or suggest the remedy for my truck.

I own a 2012 GMC Sierra 4.8 4x4, 4 speed trans and 100,000kms. (4L60E)

I have only owned the truck 4 months, but have noticed something strange about how it drives.

I place it in drive and start off. When I back off the throttle before it shifts to 2nd, the rpm will drop to idle. Then I press the accelerator pedal the rpms rise, seems like a slight slip and the gear will grab. The same applies to 2nd, 3rd and possibly 4th. But it is more noticeable in the lower gears. When I place it in manual, the truck will hold the gear, whichever gear it's placed in.

I took it to 2 transmission specialist. I finally bit the bullet and got one of them to investigate. They suspected a sprag starting to fail. Anyway, they stripped it down and found very little wrong with it. All clutches were in good condition, no signs of any leaks. The only real problem they found were some brass bits from the torque converter and one of the pistons had some scoring down one side and thought perhaps the trans was losing pressure and possibly dropping out of gear. Anyway, they installed a shift kit, torque converter, replaced the piston and rebuilt the transmission. I drove it home today and sure enough, I have the same problem. It seems to go into neutral when I back off the throttle. My buddies 2008 truck is identical and doesnt do it. I had a 2002 Silverado and that didnt do it. Does anyone have an idea what the issue could be? Does it need a software update? Or is this some kind of fuel saving feature?

Thanks in advance.

Rich
Original Poster
Rich235
Newbie
Newbie
Posts: 4
Topics: 2
Images: 1
Joined: Nov 07 2019, 5:53am
Location: BC
Year: 2012
Make/Model: GMC Sierra
Extra Info: 1500 4.8 4x4
Group Membership:
Registered users

Re: Transmission seems to drop into neutral when off gas

Postby Rich235 [OP] » Nov 19 2019, 2:05am

Since everything has settled down and all fluids have been up to temperature. I have driven about 300kms. I have isolated the issue to 1st and 2nd gear now. I believe the new torque converter has improved the shifting and made it a smoother drive. However, the rpm's still drop and it appears to be in neutral when driving in 1st and 2nd in Drive and 3. I'm taking it back to the transmission shop tomorrow. Hopefully they will have a solution.
Original Poster
Rich235
Newbie
Newbie
Posts: 4
Topics: 2
Images: 1
Joined: Nov 07 2019, 5:53am
Location: BC
Year: 2012
Make/Model: GMC Sierra
Extra Info: 1500 4.8 4x4
Group Membership:
Registered users

Re: Transmission seems to drop into neutral when off gas

Postby 2005Dirtymax » Jul 31 2020, 1:27pm

I have an 05 I have owned for 4 yrs. it does this as well. It does hold in tow haul, but not when out of that. It goes to neutral, rpms drop to idle and have to brake more rather than the trans downshifting and slowing you down. Pleases share if you find more out. I believe the torque converter is electric locked. That could be part of it.
2005Dirtymax
Newbie
Newbie
Posts: 9
Topics: 2
Joined: Jul 26 2020, 2:10am
Location: Utah USA
Year: 2005
Make/Model: Chevrolet Silverado
Variant: LT
Extra Info: 2500 HD 4X4
Group Membership:
Registered users

Re: Transmission seems to drop into neutral when off gas

Postby Rich235 [OP] » Jul 31 2020, 1:48pm

I have lived with the issue temporarily as I was a little unhappy with the shop as it wasnt fixed. I had the transmission totally stripped down, new shift kit, torque converter and a couple of other parts that had some scoring replaced. No other faults were found. Sadly the issue still resides. I have since been to another shop and the transmission tech is more than positive the issue lies in the transfer case. I can hear a clunk from it when the rpms rise as the engine connects to the wheels as I press the throttle. Once the transmission shop gets sorted due to the covid. I hope to get it back in to be fixed / investigated. They also stripped down the rear axle and all was good there. Hopefully this is the answer.
Original Poster
Rich235
Newbie
Newbie
Posts: 4
Topics: 2
Images: 1
Joined: Nov 07 2019, 5:53am
Location: BC
Year: 2012
Make/Model: GMC Sierra
Extra Info: 1500 4.8 4x4
Group Membership:
Registered users

Re: Transmission seems to drop into neutral when off gas

Postby Zrock » Aug 02 2020, 3:27pm

You are comparing your truck to 2 other older models that almost like comparing apples to oranges since some much has changed with the electronics and such... Have you tried shifting your t case into other modes to see if problem persists? The shift motor could be on its way out... I have a older truck where the shift motor is failing and it will not hold in 2hi but if i put it in auto 4x4 it holds perfectly fine...
Zrock
Shifting into Third Gear [L3]
Shifting into Third Gear [L3]
Posts: 1346
Topics: 55
Joined: Aug 06 2017, 4:34pm
Years of membership: 3 years of membership3 years of membership3 years of membership
Location: British Columbia
Year: 2003
Make/Model: Chevrolet Silverado
Extra Info: 5.3
Group Membership:
Registered users

Return to Transmission/Drivetrain

 

  • Similar topics
    Replies
    Views
    Last post

Common search terms

back issue problem transmission still truck seems drop neutral anyone installed side wheels sierra silverado thanks same rear engine

It is currently Aug 11 2020, 7:26am

  • Sponsor
Login  •  Register
Transmission/Drivetrain Forum
Transmission/DrivetrainTransmission and drivetrain related components. Discuss automatic and manual trans repairs and performance or talk about driveshafts or rear-ends and differentials. Diagnostics of 4-speed, 5-speed, or even 6-speed transmissions.
To create a new topic in Transmission/Drivetrain, click this button:
Previous topic Next topic
Sitewide News Sitemaps & Feeds

Who is online

Users browsing this forum: No registered users and 22 guests