So was driving down the interstate today....

chagan02 · October 9, 2015

I was driving to work today and was in slow interstate traffic (generally 25-45mph), thus braking and throttling. Suddenly the truck made a loud clunk. If shook the truck bad enough that my first response was to look if I had been rear-ended. Which I wasn't. Anyone had this happen?

Thanks!

chagan02 · October 10, 2015

Did some reading in another thread, perhaps this issue is related to TSB 15304?

Did anyone who had this TSB addressed have similar issues?

TimmyG · October 11, 2015

Mine did that and when i restarted later it woundt idle. Turns out my intake tube got knocked off while fixing my wipers. But some how it made it 25 miles or so to work before i had any problems

Sent from my SM-G920V using Tapatalk

BuyAmericanIron · October 12, 2015

My truck does this every day. Mostly when driving about 30 mph through our subdivision. It has rolling hills and curves. When you crest a hill and let off the gas it will upshift at the same time giving a nice clunk sound which leaves you feeling like you just got hit from behind. New passengers always ask, "what the hell was that?" Probably does it two or three times every time I drive it. Dealer says it is normal. Just another frustration and disappointment with this truck until it is gone. Working with GM on a buyback since they can't seem to get the transmission tune "right". My wife has an ATS with a six speed and it is smooth as silk. Never an issue. Why can't they apply the same tuning technology to the eight speed transmission?

thewhitestallion · October 12, 2015

yeah that has happened to me before in traffic... it is terrible

Glava2876 · October 12, 2015

I went through this and had this posted on another thread.

Hope this helps.

I just wanted to be sure this is on the site incase anyone has an A8 with a real hard 2-1 down shift bang.

My dealer had it for almost a week, but it is now FIXED!!

The tech at the dealer (Bill Rapp GMC Casey Jones)was not sending the Denali back until he was satisfied with it -man am I satisfied!

This transmission downshifts smooth as silk through all the gears ... and still goes though the gears like stink when I mash the pedal!

He did the following:

1) UPDATED TCM SOFTWARE, PERFORMED FAST LEARN ADAPTS AND ABBREVIATED COAST ADAPTIVE DOWNSHIFT ROUTINE AND VERIFIED REPAIR.

2) RECALL 15304 PROGRAMMED TRANSFER CASE SHIFT CONTROL MODULE. Prevents 4wd always engages when cold.

3) RECALL 15396 REPLACED TRANS INTERNAL HARNESS WITH INTEGRAL TFT SENSOR. Prevents harsh shift when starting in cold temperatures.

Thanks to my dealer, I am extremely pleased with my Denali!

f8l vnm · October 12, 2015

Mine at 13k still clunks everyday. It's normal is what I hear. Lol @ idiots who think it's normal. Never does it not clunk. Low speed driving kills me in this truck. With confused trans and clunk city , it annoying. Lucky for me gm has agreed to buy their lemon back

EPIC CAJUN · October 12, 2015

Yup mine does this daily in traffic when Im on and off the gas. It can scare the hell out of you at times as its so loud and unexpected. But yea, was also told from the dealer this is normal.

Tattooo · October 12, 2015

Mines done that for the past year....it gets less frequent with time, I think after the truck learns your driving patterns

chagan02 · October 12, 2015

I went through this and had this posted on another thread.

Hope this helps.

I just wanted to be sure this is on the site incase anyone has an A8 with a real hard 2-1 down shift bang.

My dealer had it for almost a week, but it is now FIXED!!

The tech at the dealer (Bill Rapp GMC Casey Jones)was not sending the Denali back until he was satisfied with it -man am I satisfied!

This transmission downshifts smooth as silk through all the gears ... and still goes though the gears like stink when I mash the pedal!

He did the following:

1) UPDATED TCM SOFTWARE, PERFORMED FAST LEARN ADAPTS AND ABBREVIATED COAST ADAPTIVE DOWNSHIFT ROUTINE AND VERIFIED REPAIR.

2) RECALL 9101695 PROGRAMMED TRANSFER CASE SHIFT CONTROL MODULE. Prevents 4wd always engages when cold.

3) RECALL 9101552 REPLACED TRANS INTERNAL HARNESS WITH INTEGRAL TFT SENSOR. Prevents harsh shift when starting in cold temperatures.

Thanks to my dealer, I am extremely pleased with my Denali!

So I have the 5.3 A6...is this why the dealership said it doesn't apply to my truck (2015 LTZ), or am I getting the run around?

chagan02 · October 13, 2015

I went through this and had this posted on another thread.

Hope this helps.

I just wanted to be sure this is on the site incase anyone has an A8 with a real hard 2-1 down shift bang.

My dealer had it for almost a week, but it is now FIXED!!

The tech at the dealer (Bill Rapp GMC Casey Jones)was not sending the Denali back until he was satisfied with it -man am I satisfied!

This transmission downshifts smooth as silk through all the gears ... and still goes though the gears like stink when I mash the pedal!

He did the following:

1) UPDATED TCM SOFTWARE, PERFORMED FAST LEARN ADAPTS AND ABBREVIATED COAST ADAPTIVE DOWNSHIFT ROUTINE AND VERIFIED REPAIR.

2) RECALL 9101695 PROGRAMMED TRANSFER CASE SHIFT CONTROL MODULE. Prevents 4wd always engages when cold.

3) RECALL 9101552 REPLACED TRANS INTERNAL HARNESS WITH INTEGRAL TFT SENSOR. Prevents harsh shift when starting in cold temperatures.

Thanks to my dealer, I am extremely pleased with my Denali!

An Update...

I just got off the phone with my local dealership again and they state a few things.

1. #15304 is a recall, but it might not qualify on my trick (as they say is doesn't) because of my build date. Does anyone know what are the qualifying build dates, and where do I find mine?

2. RECALL 9101695 & RECALL 9101552 are not recall numbers. All GM recalls start with either 15 or 15 and are five digit numbers. Said they would perform all needed TSB's and Recalls as the mechanic saw fit given the driving issues I described. I dont like the sound of that.

Glava2876 · October 13, 2015

Sorry about that, I looked at the wrong #s on the paperwork

9101695 is Recall 15304

9101552 is Recall 15396

chagan02 · October 13, 2015

Sorry about that, I looked at the wrong #s on the paperwork

9101695 is Recall 15304

9101552 is Recall 15396

No worries man. Was just making sure I was clear.

2timeGMC · December 1, 2015

Hi, Please help. My 2009 GMC Sierra - 4WD While in 2WD it first started making a loud boom when backing up occasionally. Very scary. Like you just backed into a wall. Then it starts acting normal. Now the differential( rear end ) 'I thought' completely slips making this grinding noise. The engine revs up, so have to let off the gas. When the RPM's go back down the rear end would engage again. The problem kept getting worse. Now having to drive it with front wheel drive (4 wheel high) . Is anyone having this problem? Thanks to Tow Beast I'm posting this problem under ' Transfer Case ' problems. Going to take it to the shop but would like to know exactly what the problem is first.

Thanks

Jerry

muddkatt · December 1, 2015

Hi, Please help. My 2009 GMC Sierra - 4WD While in 2WD it first started making a loud boom when backing up occasionally. Very scary. Like you just backed into a wall. Then it starts acting normal. Now the differential( rear end ) 'I thought' completely slips making this grinding noise. The engine revs up, so have to let off the gas. When the RPM's go back down the rear end would engage again. The problem kept getting worse. Now having to drive it with front wheel drive (4 wheel high) . Is anyone having this problem? Thanks to Tow Beast I'm posting this problem under ' Transfer Case ' problems. Going to take it to the shop but would like to know exactly what the problem is first.

Thanks

Jerry

Hi Jerry,

You will get a better response if you post your question in the correct forum. Here is the link:

http://www.gm-trucks.com/forums/forum/10-gen-iii-and-iv-small-block-drivetrain/