DCT Failure Code

[Fezza]

I too had a bunch of CDxx codes thrown and one time had transmission warning messages on my CIC during a hard braking event in 90+ heat. it wouldn't shift into even or odd numbered gears (can't remember which). turned the car off for a minute and restarted with no issues.

a month or two later I did a full DCT service (new fluid + filters + pan gasket) and it's been behaving super smooth since. I think our DCTs loses its sh!t when it's low on fluid since it's apparently been "designed" to leak over time.

edit: I was (and still am) running the GTS tune as well.

[JaviV8]

Hello all, greetings from Madrid in Spain. I have been suffering these four codes for a while.
My old battery was arriving to the end, launching "low battery" alert very often. One day, suddenly, it launched the “gear fail” signal and I was stucked in P. Like you say, if you turn off and let him 3 minutes, you restart and failure is gone. I was convinced it was something from the low voltage.
I replaced battery and it was apparently solved. BUT, after some time, it came back.
I do not care making the DCT maintenance, the car is only 83.000 km = 52.000 miles, but it is a 2012 car so… it is the time.
BUT, my fear is that that does not solve the problem. I suspect the voltage is low in the battery (I see it on the OBD2 connection), and I wonder if the alternator is not charging the new battery properly…
Anyone has news or update in this matter?
Thank you!

[JaviV8]

Hello all!

Just let you know that my ground strap was totally loose. I think they forgot to tight it properly after rod bearing substitution... so... well, now I have to observe it... but I bet problem is finally solved.

Before going to the shop, I made an easy test measuring with a voltmeter (car started, lights and air on) between the engine block (from the ring for lift it) and the ground point in the body (in the left part of the body, close to the VIN number in the bumper). If it is good, voltage there should be 0 (the engine block is connected to ground throughout the ground strap). When my ground was loose it was more than 0,7 volt!!

Because of this I asked my mechanic directly to check the main ground strap (you have to lift the car and remove carter cover for easy access), and that was there: Loose cable. We saved time!

Alter tightening again, measured voltage came to 0, or 0,02 maximum.

Well, I have to observe it. But I dare to say that was the issue.

Thank you to all, especially the mates with the same or similar problems that helped here, or by privete message!

Javier.

[JaviV8]

Just confirm to all of you that my problem was totally solved by fixing ground strap. It was loose, the mechanic forgot to fix properly after rod bearings replacement... and the "crazy crank issue" started.

In my case I was also convinced that it was a voltage issue during cranking. Because ONLY happened at starts, and only a few times. When the fail did not appear, it waorked perfectly.

If you see this:







Yo see the voltage during CRANKING, before, and after fixing the ground strap. The battery is the same, a new one. CLEARLY there is more than 1 volt "leaking" anywhere.

This peaks made the DCT "crazy". And not always. And of course, the stronger the battery is, the less you get the fail.

In the other picture, I messuared with a voltmeter between engine, and ground point (with engine ON, lights and conditioned air ON). I was able to see more than one volt. That meant the engine was not properly "grounded". After fixing the strap, I messure 0,02 volt at much.

I think it is a good idea to monitor the voltage in a "healthy car" during cranking, and compare to the "failing" car. At least in my case you can clearly realize the difference.

Now the car is working perfectly. I wonder what can happend if I stay long with the problem. May be the battery and the alternator can fail... or may be the ECU can be damaged... I don´t know.

Good luck!

[JaviV8]

Here you can see the FAILS the problem created. A lot of them. All of them FAKE. After fixing the issue, NO SINGLE FAIL is shown. Incredible. This ground strap is "dangerous". You can imagine I got very happy with the mechanic. At least we found it ans solved it quickly. Noone is perfect!

Regards,

Javier.

[Tallicia]

I conclusively found the issue. It's the alt/strtr/b+ cable. Stealershiip damaged it and once replaced, absolutely zero issues for months now.

It also mad my valvetronic behavior so much better.

Proper wiring/cabling/voltage is so important.

Of course, right after doing the cable, the next day it happened a few times. It was trying to recalibrate with proper voltage. I reset all adaptations the next day and all has been perfect.

It feels great to have forgotten how annoying this was. Yay!

[johnnyroyal]

Just wanted to add to this thread.

I had the following codes 5A48 5A55 5073 and 5074. My car has 57k miles on it, RB's done along with TA's. When driving the car I noticed 0 issues with the transmission. It drives like it did when it came off the lot.

I was getting the Transmission Malfunction code every so often and was not able to get my car out of park. After starting and stopping the car 5-10 times I was able to finally get the car to start.

I replaced the battery, got a battery tender, replaced the alternator, and didn't have any luck. I finally replaced the ground strap, cleared the errors and thankfully I haven't had any additional errors. I would recommend starting with the ground strap, it would have saved me a few dollars.

I'm not too upset about the new parts I put in the car, but its crazy to think all of this was due to a grounding problem. Hope this helps someone in the future.

[UnicornM]

Having same issue it seems on my E90 M3 (80k miles) I don't daily it infact it wasnt driven for about 3 months or so and today I had all the transmission warning lights and abs etc... after a 200 mile round trip lost all ability to use cruise control.

The lights on the DCT knob no longer change colour or intensity when selecting D or R etc... and I noticed right before it when in P if you ever so slight touched the DCT knob the instrument cluster display flickers from N to P randomly.

Is this related to ground too? If so which ground strap?

[UnicornM]

Fast forward to this morning. The DCT knob illumination is back and working. Did a resistance check on grounds at the locations and its 0 Ohms.

I suspect it was just from being sat for a long time? I do recall I was 70 miles into my journey before the error appeared and it was almost same time I turned the air con on. Anyway, I will do several short trips over the next few days and hopefully its sorted itself out. I have a 1800 mile trip to Austria next week so could do with my anxiety put to rest, well somewhat haha

[mikerunt]

Originally Posted by UnicornM

Fast forward to this morning. The DCT knob illumination is back and working. Did a resistance check on grounds at the locations and its 0 Ohms.

I suspect it was just from being sat for a long time? I do recall I was 70 miles into my journey before the error appeared and it was almost same time I turned the air con on. Anyway, I will do several short trips over the next few days and hopefully its sorted itself out. I have a 1800 mile trip to Austria next week so could do with my anxiety put to rest, well somewhat haha

I’m currently dealing with this same issue of now lights in the DCT knob when is causing a no start condition.

[UnicornM]

Originally Posted by mikerunt

I’m currently dealing with this same issue of now lights in the DCT knob when is causing a no start condition.

Mine starts, drives and goes through the gears fine. Though when it first happened it was set on cruise at 70mph turned on the A/C and it just started acting goofy.

I have a spare DCT knob but I didn't even need to try it, I cleared the codes and took it for a 5 mile drive and its been ok.

It could be related to the battery, I just re-registered it as I have a 30ah Lithium so done it as a 60ah AGM via bimmergeeks.

Hopefully it was just a blip but who knows

[Bmwdoubles_]

The issue for me after two new DCT levers and the dealer never disclosed except at the end where the service guy secretly texted me the hint. It’s mostly due to the AC drain getting disconnected and the moisture creating crazy condensation right by the lower connection of the DCT lever. There are two pigtails. The first one you see right away when you lift the shift boot cover up. The second is when you unbolt the dct. That lower pigtail, if rusted, is what causes problems. Replacing the drain connection is a biatch and involves removing a bunch of the center console and lowering the dct. So when I had the new lever installed and coded in I packed the connectors with a bunch of dialectic grease. So far so good and it’s been a year. More humidity is caused when you’re windows are down and you’re running your ac.

[UnicornM]

Originally Posted by Bmwdoubles_

The issue for me after two new DCT levers and the dealer never disclosed except at the end where the service guy secretly texted me the hint. It’s mostly due to the AC drain getting disconnected and the moisture creating crazy condensation right by the lower connection of the DCT lever. There are two pigtails. The first one you see right away when you lift the shift boot cover up. The second is when you unbolt the dct. That lower pigtail, if rusted, is what causes problems. Replacing the drain connection is a biatch and involves removing a bunch of the center console and lowering the dct. So when I had the new lever installed and coded in I packed the connectors with a bunch of dialectic grease. So far so good and it’s been a year. More humidity is caused when you’re windows are down and you’re running your ac.

Interesting! So far my DCT knobs are illuminating as they should. I haven't driven or used the car for around 4 maybe 5 months so its likely a similar issue?

[Bmwdoubles_]

Originally Posted by UnicornM

Interesting! So far my DCT knobs are illuminating as they should. I haven't driven or used the car for around 4 maybe 5 months so its likely a similar issue?

Take out the DCT and check. Have you ever had water hit your leg or the passenger or had wet/damp carpet? If so, the drain is disconnected. If your dct is still working and moisture is the issue, you can save the lever before it shorts. Pull the lever and check for rust, then stuff it full dialectic grease. I will check mine, and I’ll post back here on how the grease is holding up.

[UnicornM]

Originally Posted by Bmwdoubles_

Take out the DCT and check. Have you ever had water hit your leg or the passenger or had wet/damp carpet? If so, the drain is disconnected. If your dct is still working and moisture is the issue, you can save the lever before it shorts. Pull the lever and check for rust, then stuff it full dialectic grease. I will check mine, and I’ll post back here on how the grease is holding up.

No water, no rust nothing of the sort. As a note it barely covers 1000 miles a year. Before all this came about it had be parked up for 5 months. I've changed rear wheel sensor as it came as one of the faults when I had errors pop up on the scanner. I have a spare DCT knob and just for the hell of it I have swapped it. I haven't done any long distance driving (I will be in a few days) so I can't really be sure if this is all just waiting to pop up again!

I will be sure to report back

[Helmsman]

Originally Posted by UnicornM

Mine starts, drives and goes through the gears fine. Though when it first happened it was set on cruise at 70mph turned on the A/C and it just started acting goofy.

I have a spare DCT knob but I didn't even need to try it, I cleared the codes and took it for a 5 mile drive and its been ok.

It could be related to the battery, I just re-registered it as I have a 30ah Lithium so done it as a 60ah AGM via bimmergeeks.

Hopefully it was just a blip but who knows

Btw depending on what Lithium battery you put in, might be worth reading Redd's notes on charging issues with his Lithium battery towards the end in this thread:
https://www.m3post.com/forums/showthread.php?t=1646308&page=2

[UnicornM]

Well, I drove 1800 mile round trip to Austria (from UK) and no dramas until the return leg. Pretty much all the Christmas tree lights on the dash. The flickering from 'P' & 'N' came back with key set to position 2. Mechanically zero issues.

I'll pull up the codes later, but I have a hunch on one potential issue. Rear ABS/Wheel sensors. I noticed squeaking from the rear which suggest e-brake shoes need adjusting. Potentially causing rear axles/wheels to heat and as such throw off sensor values.

[UnicornM]

Originally Posted by Bmwdoubles_

Take out the DCT and check. Have you ever had water hit your leg or the passenger or had wet/damp carpet? If so, the drain is disconnected. If your dct is still working and moisture is the issue, you can save the lever before it shorts. Pull the lever and check for rust, then stuff it full dialectic grease. I will check mine, and I’ll post back here on how the grease is holding up.

Potentially could be my issue however no water or moisture when pulling off the shift knob? Hows yours holding up?