2015 GMC Denali 6.2/8-speed shifting noise when cold

[Ashtonman]

I am having a metal clunking/clapping noise when the truck is stating from a stop when it is cold. Noise only happens if I am starting at a very slow speed in traffic.

If I take off quickly it does not happen. Truck has about 1800 miles on it. It does not happen every time, it stops if I drive it more than 10-15 miles. Won't do it again until it is cold.

I think it's an exhaust or heat shield issue. It's kind of a higher pitch metal slap.

I have not been back to the dealer yet. Anyone else having this issue.

[BluByU14]

I am having a metal clunking/clapping noise when the truck is stating from a stop when it is cold. Noise only happens if I am starting at a very slow speed in traffic.

If I take off quickly it does not happen. Truck has about 1800 miles on it. It does not happen every time, it stops if I drive it more than 10-15 miles. Won't do it again until it is cold.

I think it's an exhaust or heat shield issue. It's kind of a higher pitch metal slap.

I have not been back to the dealer yet. Anyone else having this issue.

 

I noticed a slight delay (2-3 seconds), followed by a minor clunk when the trans shifted from 1st to 2nd....mainly when it was cold out. Now, I only have 175 miles on my truck so the motor/trans is still getting use to my drive style. When driving it to work this morning, I did not notice the issue. Will report back if see, hear or feel any issues.

[BluByU14]

I am having a metal clunking/clapping noise when the truck is stating from a stop when it is cold. Noise only happens if I am starting at a very slow speed in traffic.

If I take off quickly it does not happen. Truck has about 1800 miles on it. It does not happen every time, it stops if I drive it more than 10-15 miles. Won't do it again until it is cold.

I think it's an exhaust or heat shield issue. It's kind of a higher pitch metal slap.

I have not been back to the dealer yet. Anyone else having this issue.

I actually just started to experience this on my way home from work. Heard it twice pulling from a stop while cold. Once it got warmed up...went away. Same symptom you are describing.

[redwngr]

Mine clunks to. I'm not yet convinced the clunk is transmission.

(although maybe driveline due to the way the trans shifts)

[Horacio]

Mine has the same issue when shifting from 1st to 2nd when cold...slight delay and then the clunk

Only 50 miles on mine.

[BluByU14]

Mine clunks to. I'm not yet convinced the clunk is transmission.

(although maybe driveline due to the way the trans shifts)

 

I agree...it is not a strong clunk or jolt of any kind. I haven't finalized all of the buy-back paperwork as of yet, so when I go back to the dealer to sign the papers, I will bring it up to them and have then check it out. At this point I am not going to worry about it.....truck, trans, and performance is 10x better than my 14 Sierra.

[crushNchowda]

Assembled in the good old US of A!

I think you missed my sarcasm...my buddy is now on his THIRD truck, he now has an 8 speed 6.2 denali fully fully loaded, had a '14 5.3 6 speed denali, and before that a 5.3 6 speed SLT. Now he is complaining about this one too - tranny, throttle tip in, power isn't as advertised (maybe he should try breaking it in though thing has all of 500 miles lol)

 

Bottom line is, I have never, EVER been to a forum w/ so many constant complaints. Is my truck perfect? NO, but I'm going to live with it because nothing in life is perfect and the grass is always greener etc. That, and the fact that GM royally F****D every single loyal owner in the rear that bought a 2014 early on w/ this absolutely RIDICULOUS rebates and incentives has completely turned my off from the badge, I don't even want to look at the dealers let alone step foot on the lot, so I'm all set with trading up or sideways for another (been there).

My real advice is, just like the 6 speeds, wait until some reputable tuner has tunes available and/or head to the dyno. I don't know what it is exactly about GM and their transmission programming, but it is essentially the worst in the industry IMO - and a big detractor for me. The clunking, delayed shifts, rpm surges in seemingly neutral, confusion of when to up or down shift, refusal to shift, and bad behavior in the cold? Yeah, that is pretty much par for the course from GM.

 

I should know - 3 trucks, a G8 GT, and a caddy CTS should be enough of a test sample..

[Ashtonman]

Update, I took my truck back to the dealer today for service today. I was able to duplicate the shifting noise for the tech. The metal slapping noise is getting worse everyday. It is now happening when downshifting. I have 2031 miles on it and looks like it's the transmission/transfer case. He found some info on the computer about it but there is no update. There was an engine update and he reset the transmission computer. He said he would keep an eye out for an update but I have the only 6.2/8 speed truck he has seen so far. I am sure there will be a fix for this, if they have to replace the transmission so be it. It's still a great truck.

[BluByU14]

Update, I took my truck back to the dealer today for service today. I was able to duplicate the shifting noise for the tech. The metal slapping noise is getting worse everyday. It is now happening when downshifting. I have 2031 miles on it and looks like it's the transmission/transfer case. He found some info on the computer about it but there is no update. There was an engine update and he reset the transmission computer. He said he would keep an eye out for an update but I have the only 6.2/8 speed truck he has seen so far. I am sure there will be a fix for this, if they have to replace the transmission so be it. It's still a great truck.

 

Thanks for the update. I would hope that it is just an update they can make to the transmission's tuning, etc, without the need for total transmission replacement. I will keep you posted if my truck seems to get worse. Right now it only happens when it is cold....after that the trans seems very smooth. I do notice the hard downshift when coming to a stop (3rd to 2nd..2nd to 1st)....that does sometimes come with a "clunk", but my 2014 6-speed did the same thing and was told it was normal for these trucks.

[LawmanSS]

FYI, there's a service bulletin out about harsh shifting in the 8-speed transmission. It's dated December 2014, bulletin #14876.

[MS3DALE]

Service Bulletin

GM Bulletin No.:

Date:

 

 

14876

December 2014

 

 

 

Service Bulletin

GM Bulletin No.:

Date:

 

 

14876

December 2014

 

 

 

Service Bulletin

 

GM Bulletin No.:

 

Date:

 

14876

 

December 2014

 

SERVICE UPDATE

 

SUBJECT: Service Update for Inventory Vehicles Only

 

8-speed Transmission Harsh Shift

 

Expires December 31, 2015

 

MODELS: 2015 Cadillac Escalade, Escalade ESV

 

2015 Chevrolet Corvette, Silverado Double Cab and Crew Cab

 

2015 GMC Sierra Double Cab and Crew Cab, Yukon, Yukon XL

 

Equipped with 8-speed Automatic Transmission (M5U)

 

This service update involves vehicles in dealer inventory only and will expire December 31,

 

2015.

 

PURPOSE

 

On certain 2015 model year Cadillac Escalade, Cadillac Escalade ESV, Chevrolet Corvette,

 

Chevrolet Silverado Double Cab and Crew Cab, GMC Sierra Double Cab and Crew Cab, GMC

 

Yukon and GMC Yukon XL vehicles equipped with 8-speed automatic transmission (M5U), the

 

customer may complain about harsh shifting. This can occur if the vehicle experienced multiple

 

transmission reprogramming events during manufacturing, causing the calibration to over-adjust

 

the shift parameters. This bulletin provides a service adaptive learn procedure that should be run

 

to reset the calibration to the baseline parameters.

 

This service procedure should be completed on involved vehicles currently in dealership

 

inventory as soon as possible but no later than December 31, 2015, at which time this

 

bulletin will expire.

 

VEHICLES INVOLVED

 

All involved vehicles are identified by VIN in the Global Warranty Management System –

 

Investigate Vehicle History Application. Dealership technicians should always check this site to

 

confirm vehicle involvement prior to beginning any required inspections and/or repairs. It is

 

important to routinely use this tool to verify eligibility because not all similar vehicles may be

 

involved regardless of description or option content.

 

Additionally, a list of involved vehicles currently in dealer inventory is available on the “Service

 

Update Bulletin Information” link under the “Service” tab in GM GlobalConnect (US) or attached

 

to the GlobalConnect message (Canada) used to release this bulletin. Customer vehicles that

 

return for service, for any reason, and are still covered under the vehicle's base warranty should

 

also be checked for vehicle eligibility.

 

Page 2 December 2014 Bulletin No.: 14876

 

PART INFORMATION

 

No parts are required.

 

SERVICE PROCEDURE

 

Note: Ensure the most recent GDS2 update is installed BEFORE performing the procedure.

 

Note: If the transmission fluid temperature is not between 75°C (167°F) and 85°C (185°F) the scan tool will not allow you to perform the service fast learn procedure.

 

1. Drive vehicle to warm transmission fluid to a temperature range between 75°C (167°F) and 85°C (185°F).

 

2. Connect the MDI to the vehicle.

 

3. Access GDS2 and navigate to the Transmission Adaptive Values Learn screen using the following GDS2 navigation path: Diagnostics>Global Vehicle Selection>Module Diagnostics>Transmission Controls>Configuration/Reset Functions>Transmission Adaptive Values Learn.

 

Note: After the Transmission Adaptive Value Learn procedure is performed, the ignition must be shut off for at least two minutes to ensure the transmission control module shuts down completely before the vehicle is driven. This reboot of the transmission control module is needed before the transmission control module will operate under the new learned values.

 

4. Follow Transmission Adaptive Values Learn on-screen instructions. Refer to Transmission Service Fast Learn Procedure in SI if required.

 

5. Remove MDI from the vehicle.

 

6. Verify transmission shifts into ‘R’ Reverse and ‘D’ Drive.

 

WARRANTY TRANSACTION INFORMATION

 

Submit a transaction using the table below. All transactions should be submitted as a ZFAT transaction type, unless noted otherwise.

 

Labor Code

 

Description

 

Labor Time

 

Net Item

 

9101182

 

Perform Transmission Adaptive Values Learn Procedure

 

0.5

 

*

 

* The amount identified in “Net Item” should represent the actual sum total of the current GMCCA Dealer net price for fuel needed to perform the required repairs, not to exceed $1.50 USD, $2.40 CAD, plus applicable Mark-Up or Landed Cost (for Export).

 

DEALER PROGRAM RESPONSIBILITY

 

Whenever a vehicle subject to this service update enters your vehicle inventory, or is in your facility for service in the future, and the vehicle is still covered under the New Vehicle Limited Warranty, you must take the steps necessary to be sure the service update correction has been made before selling or releasing the vehicle.

[redwngr]

Last paragraph may be the most important to those with harsh shifting.

[BluByU14]

Last paragraph may be the most important to those with harsh shifting.

 

So this may be dumb question....but.....I took delivery of my truck on 12/26/14. The truck was ordered as a part of a GM Repurchase case. I started experiencing these "harsh" shift within the first few hundred miles. Made mention of this to my service adviser on Friday 1/2/15 and he said that there it is normal. Is it worth forwarding these service bulletin to the dealership? Would they have checked for this in the Pre-Delivery Inspection?

[SMiller]

 

So this may be dumb question....but.....I took delivery of my truck on 12/26/14. The truck was ordered as a part of a GM Repurchase case. I started experiencing these "harsh" shift within the first few hundred miles. Made mention of this to my service adviser on Friday 1/2/15 and he said that there it is normal. Is it worth forwarding these service bulletin to the dealership? Would they have checked for this in the Pre-Delivery Inspection?

I assure you they did not update it, they run it through prep as fast as they can, print out the tab and take the truck in.

[LawmanSS]

Service Bulletin

GM Bulletin No.:

Date:

 

 

14876

December 2014

 

 

 

Service Bulletin

GM Bulletin No.:

Date:

 

 

14876

December 2014

 

 

Service Bulletin

GM Bulletin No.:

Date:

14876

December 2014

SERVICE UPDATE

SUBJECT: Service Update for Inventory Vehicles Only

8-speed Transmission Harsh Shift

Expires December 31, 2015

MODELS: 2015 Cadillac Escalade, Escalade ESV

2015 Chevrolet Corvette, Silverado Double Cab and Crew Cab

2015 GMC Sierra Double Cab and Crew Cab, Yukon, Yukon XL

Equipped with 8-speed Automatic Transmission (M5U)

This service update involves vehicles in dealer inventory only and will expire December 31,

2015.

PURPOSE

On certain 2015 model year Cadillac Escalade, Cadillac Escalade ESV, Chevrolet Corvette,

Chevrolet Silverado Double Cab and Crew Cab, GMC Sierra Double Cab and Crew Cab, GMC

Yukon and GMC Yukon XL vehicles equipped with 8-speed automatic transmission (M5U), the

customer may complain about harsh shifting. This can occur if the vehicle

Thanks, Rich!