03 Denali Tranny..

I just got a new Denali and I have a question. When I am cruising along around 40-50 and then have to break for a stop sign, a (feel) of a clunking can be felt through the gas pedal. It feels like the transmission is down shifting kinda but it shouldn't clunk. Anyone every heard of this? I can only feel it when I get down to around 5-10mph, it does it once and then not again until I slow back down, I am thinking of having the dealer take a look at it since there are only 700 miles on it, but part of me thinks it could be normal.. Any Thoughts?

Whether it's normal or not is hard to say but if it concerns you make an appointment at the dealer to get it checked out.

:( My 03 Denali has the same problem, took it to the dealer and the the gave me a letter from GM stating that the clunk was from reverse torque, a normal condition and don't attempt to repair.
I hate that clunk! specially on 50k truck

Are you serious??? I have only 2K miles on this thing.. My 30,000$$ Acura doesn't do that, you would think they would figure it out.. Anyway thanks for the input..

These sites are great to help maintain your sanity. My new 03 D does the same thing as I come to a stop. Same clunk, same annoyance, same frustration about the act. Do we know for sure what the issue is and that it is not a concern?

Okay, so I'm not the only one who has that problem; my '03 YXL does the exact same thing, although I feel the clunk more through the brake pedal rather than through the gas pedal since my foot usually remains on the brake pedal when I'm hitting the brakes to slow down...;)

I know mine clunked all the way up until it broke at 60k miles...

Guys,
My 2000 Yukon had a clunk that I felt in the Steering wheel and brake pedal. It turned out to be the upper intermediate steering shaft. There is a lube kit and TSB for it.

If you are still under warrenty, I would have them lube the upper intermediate steering shaft. It fixed my clunk.

Good Luck.

//2000CAYukon

We had the clunk (coming to a stop - like the tranny was holding gear just a bit too long before releasing) on my wife's '03 Denali from the day we took it home. I had it into the shop a few weeks later for them to look into it. The technician did a little research, and then got ahold of a reflash that addressed some tranny issues.

After the reflash, the clunk went away (still gone 5k miles later). The reflash also fixed an intermittent "shift hunting" condition, and firmed up the shifts just a bit. However, I've noticed that the tranny is still a bit soft for my taste, but using the tow/haul mode during acceleration seems to tighten things up a bit - it raises the shift points, which is definitely something you want for towing. Although I wish the tow/haul mode was more like what you get on the Allison tranny.

What's a reflash?

A Reflash is a new program for the tranny. They remove the old flash and install a new one which contains the new shift points.

What's a reflash?


The dealer service technician "reflashes", or updates programming in the vehicle computer, based on issues that arise once the vehicles are out on the roads, etc. They download the software upgrades onto their hand held diagnostic scan tools, then download the upgrades to the vehicle computer via the diagnostic port (like the ones on the back of your computer) that is located in-cab.

The manufacturers of the power programmers (Hypertech, Superchips, etc) have also taken advantage of those same in-cab diagnostic ports to allow you to download power enhancing programs and to be able to read error codes when your Service Engine Soon, etc. lights come on.

Thanks!