bdstrak

Guys,
My 2014 C7 (27K miles) A6 (6L80) has been at the local dealer all week and the tech can't diagnose my transmission issue. The problem is this: Starting from a stop in Drive, tranny always starts in 2nd gear. During light load acceleration, the torque converter attempts to lock up multiple times between ~30 - 44 mph. Once at 45 mph, the converter locks, RPMs drop and from there on, all is good...until I stop and start again.
There does not appear to be any issues with the 8/4 deactivation.
Tech initially thought I had entered a valet code which caused it to launch in 2nd gear. I told him I had never used that function. He then reprogrammed the tranny to reset a possible valet code. That did allow the car to launch in 1st gear but for only the first 15 minutes of a test drive. It then defaulted back to launching in 2nd gear again.
Dealer has now queried tech assistance from GM because the tech can't determine if my problem is a software or hardware issue.
Can anyone provide any information to assist the diagnosis of this issue? Appreciate any assistance.

eboggs_jkvl

I have noticed that when running the paddles in "manual" mode, when I stop and let the car downshift, it only downshifts to 2nd. If I don't tap the paddle to first, it will start out in 2nd and await my paddle push to climb up through the gears. I can down shift to first when I'm doing say 30 or so, it'll let me paddle down to 1st but if I let the A6 walk down the gears to a stop, it'll sit at 2nd.,


I've always assumed it was going to 1st when I stopped while in "D". Maybe I'm only going down to 2nd when it's in D??? I plan on making a run to a store in a minute. I'll run in D and peek at the gear when I stop and see if it dropped to 1st or 2nd.

Elmer

Rebel Yell

I think this is the first post I've seen concerning problems with the A6. I'm going to take a SWAG here, and say since after re-programming the tranny worked for the first 15 minutes then with back to it's old ways it may be a software problem. But, I have been known to be wrong on occasions, just ask my wife. Good luck, I hope it's nothing serious.

Zymurgy

That's the way the A6 worked back in the C6. If you used the paddles, it would only downshift to 2nd on its own. If you leave it in Drive (no paddles), it will downshift to 1st on its own.

eboggs_jkvl

OK, confirmed what I said. In drive it goes down to 1st. I stopped at a light, slipped it into "M" and it indicated that it was in 1st. In Manual with the paddles, it goes down to 2nd and must be paddled down into 1st.

Elmer

cowboy casey

I will see on the way home..

eboggs_jkvl

Please confirm for me that you have the car in Drive, stop, and then pull the shifter back into Manual and the dash says 2nd. Is that correct?

cowboy casey

Confirmed exactly this in my A6...

owc6

Mine has always come to 1st in D when coming to a stop. In M it will only come to 2nd when stopping. I will then have to downshift if I want to start off in 1st ( in M).

When in M, no matter what gear I am in when stopping, it will not shift into first when I come to a complete stop. The default gear is 2nd.

bdstrak

The A6 is in Drive. The dash displays D, no specific gear. At a stop still in D, it will start in 2nd gear. The only way I can get it into 1st is to go into Manual and paddle shift to 1st.
My real concern is the torque converter trying to lock up between ~28 and 44 mph under a light load or on an incline. It attempts to lock but it won't hold and the engine revs keep changing until <45 mph. Does anyone else have this torque converter issue?

phileaglesfan

Normal operation! All my C6s did the same.

Something is wrong in your case. A6 was a pretty solid tranny, seems to be a lot more reliable than the A8.

eboggs_jkvl

I've noticed a few instances with, for want of a better word, slipping while changing gears. I can't find a pattern or be able to make it happen "on command" so I'm ignoring it until it gets bad enough to go to the dealer.

Elmer

LIE2ME

Wow, my A6 has been flawless. I hope this all works out for you...

bdstrak

OK, here's an update from the dealer on my A6 torque converter issue. After a day in the shop, the service tech called to ask me for the valet code that I entered. I told him I never used that capability. The next day he called to tell me that the mechanic was going to download and install the A6 software in order to defeat the valet code. After that was installed, he called to report the fresh SW did not fix the problem and they were requesting GM's assistance. On the sixth day I was informed that they were ordering a new Transmission Control Module. I told the service tech that I really needed a car for a couple of days. He offered me a loaner to use until the TCM was received and installed. I'm now driving a 2018 loaded 1.5L turbo Malibu. All shop time, parts, and loaner are covered by GM. I hope the TCM does the job once my ride is returned to me.

Kraz8s

Good to hear! My 2014 is the only non- professionally tuned A6 I've owned, had a 2012 5th Gen SS and a GS.

The 2014 A6 definitely has it's quirks but nothing like yours. I can say that mine likes to run hot and with TC off though.

Hope they get it fixed for you, nothing worse than a car in a shop that isn't there for mods.

dbdave

Do you have a base car or Z51? I'm thinking this is normal. My base car works like this. I never thought about it until someone pointed it out in another thread. The Z51 A6 may be programmed differently than the base car?

Under light load, there is some searching for the right gear in my '14 which may be what you are seeing as a torque converter problem.