DCT Transmission Malfunction, won't go into gear!

[Alexand3r]

Hello fellow owners!

My turn had come, to deal with the Gearbox malfunction problem.
It happened suddenly, out of nowhere, after I drove it a few times that day.
Started the car and I got the message. Gear lever does not respond to any command. One strange thing I noticed is that the car hesitates when it starts, like the battery is weak, which I don't believe is the case, because it's relatively new battery.

Attached is a photo of the errors in the module, which are there only when the engine is working. After I clear them, nothing changes and when I scan them again, they are there again.

The gearbox has GTS tune. Oil was changed few months ago and I even added a bit more(0.5 liters), because of the tune.

No problems whatsoever until today. Any help would be highly appreciated!

[wfdeacon88]

This is why I've never done the GTS tune... not saying it's related necessarily, but I've heard and read of a decent amount of tranny issues potentially coming from these DCT tunes. have you tried reflashing back to stock?

[Unwritten-dinasty]

Originally Posted by wfdeacon88

This is why I've never done the GTS tune... not saying it's related necessarily, but I've heard and read of a decent amount of tranny issues potentially coming from these DCT tunes. have you tried reflashing back to stock?

Any links to such threads? All I read is that the GTS tune is one if not the best mod you can do to our cars so I've been really considering it the past few weeks.

[wfdeacon88]

Originally Posted by Unwritten-dinasty

Any links to such threads? All I read is that the GTS tune is one if not the best mod you can do to our cars so I've been really considering it the past few weeks.

Replacing DCT - Many issues, CAS Module Bricked https://www.m3post.com/forums/showthread.php?t=1665367

here's one.. scroll down to his post on his mods.
I am no expert, I am no claiming to know it is a risk to tune it, but over the last two years on here, just a few too many threads and conversations have scared me away from doing it ... mines been solid at 116K miles, so I'm probably a minority of cautious people on this.

[nyc_dude]

I had a DCT failure. $15k USD Lots of work to update the SW after the new DCT install.

Check with deansbimmer in Dallas, Texas and he may have a used DCT.

Two other options. Replace the internal pump and/or replace the mechatronics unit.

Before trying to repair the DCT, check the fuel pump under the back seats. (2 pumps). $1k USD to replace...very easy. Check youtube. EKP module for the fuel pump is behind the back seat upright.

When your DCT fails while driving the car shifts into Neutral for safety and your rpms drop to near zero.

My DCT and fuel pump failed at the exact same time. BMW dealer didnt fix the fuel pump first. They also don't repair DCT internals. $16k USD.

Good Luck,


Cheers,

[akkando]

Originally Posted by wfdeacon88

Replacing DCT - Many issues, CAS Module Bricked https://www.m3post.com/forums/showthread.php?t=1665367

here's one.. scroll down to his post on his mods.
I am no expert, I am no claiming to know it is a risk to tune it, but over the last two years on here, just a few too many threads and conversations have scared me away from doing it ... mines been solid at 116K miles, so I'm probably a minority of cautious people on this.

It's unclear to me it's a risk on the street. The GTS tune is a popular mod.

[KawBoy]

I dont think it is the GTS maps; I change maps all the time and no issues.
At the same time, I dont think your tranny is bad. A lot of guys here have the expertise to re flash it for you.

[Makaveli7]

This happens when you have a bad battery/alternator as suggested by the first code that you have - I was dealing with this in my friend's car a couple of days ago. check the alternator and the battery before you jump into the DCT. The car had the same Valve errors, we jump-started it, left to run, turned it off, left it to reset and it worked. I hope its a simple fix and nothing serious.

[KawBoy]

Originally Posted by Makaveli7

This happens when you have a bad battery/alternator as suggested by the first code that you have - I was dealing with this in my friend's car a couple of days ago. check the alternator and the battery before you jump into the DCT. The car had the same Valve errors, we jump-started it, left to run, turned it off, left it to reset and it worked. I hope its a simple fix and nothing serious.

+1

[Sandye90m3]

Originally Posted by wfdeacon88

This is why I've never done the GTS tune... not saying it's related necessarily, but I've heard and read of a decent amount of tranny issues potentially coming from these DCT tunes. have you tried reflashing back to stock?

lol, that's like me saying "that's why I don't drive my car in the rain"..

I've had that software update for 120k out of 140k of my ownership and nothing has ever happened.

The GTS uses the same software and has the same hardware as any other M3.

[Alexand3r]

Originally Posted by Makaveli7

This happens when you have a bad battery/alternator as suggested by the first code that you have - I was dealing with this in my friend's car a couple of days ago. check the alternator and the battery before you jump into the DCT. The car had the same Valve errors, we jump-started it, left to run, turned it off, left it to reset and it worked. I hope its a simple fix and nothing serious.

Thanks for that!

Well it turns out, it really is one of the two. Left the car, came back to it later and everything was fine. Will investigate the battery first, because I had the alternator refurbished a few months ago. Will report back!

[sdbmwcoding]

Run a test plan on the DKG codes on ista. It'll give more information on everything. Could be failing mechatronics unit, I've seen a few of those lately which show symptoms of intermittent transmission issues like you're experiencing.

[Alexand3r]

Let's blow the dust off..

Just wanted to inform anyone who can have similar problem in the future. It was an electrical issue after all.
After some investigation, turned out, that the grounding cable for the engine, the one that goes from the oil pan to the body of the car, was a bit loose. So from there on, when the car was starting, the voltage of the engine and the transmission, was falling down to 6V and therefore the transmission recorded an error.

So if this happens to you, it 99% is an electrical issue, that triggers a low voltage alarm in the gearbox!

[4130]

Originally Posted by Alexand3r

Let's blow the dust off..

Just wanted to inform anyone who can have similar problem in the future. It was an electrical issue after all.
After some investigation, turned out, that the grounding cable for the engine, the one that goes from the oil pan to the body of the car, was a bit loose. So from there on, when the car was starting, the voltage of the engine and the transmission, was falling down to 6V and therefore the transmission recorded an error.

So if this happens to you, it 99% is an electrical issue, that triggers a low voltage alarm in the gearbox!

Thanks for posting this follow up. Glad you figured it out and it wasn't anywhere near as big a deal as you initially suspected.

[Timujin]

Nothing a solid conclusion! Great news!