DCT Software Versions, Hard Shifts, Transmission Malfunction Question

[F18 Hornet]

Hello Forums,

So I'm at my wits end on my E92 M3. This is the 4th M3 I've owned and the only one that has caused me problems and I'm beyond done with attempting to sink money into it.

Here's the issue:

- Car throws following codes:
CF27 Message (operation, gearbox selector switch 2, LIN) from GWS
5A48 Control valve PV6: short circuit/winding fault
5A55 Control valve PV7: Short circuit/winding fault
5073 Supply of valve group 2: faulty
5074 Supply of valve group 3: faulty
E094 No message (display transmission data) from the electronic transmission control, receiver gear selector switch, transmission electronic transmission control/Sequential Manual Gearbox SMG/twin-clutch gearbox

- Transmission shifts hard (Feels like if you drive and dumped the clutch on a manual)

- Battery seems to crank a few times before starting (sounds weak/low battery, but it was just replaced).

Now, the car is a February 2013 build. I also have a May 2013 build and none of these occur.
Could there have been a software update between that might've changed anything?
Could the hard shifting be due to an older version DCT software?
Is there a chance this could be a DCT computer problem?
Is it a Mechatronics failure?

I know I posted something similar, but I've noticed this occurring as well.
I might have the transmission fluid changed out again to see if anything else is different.

[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!

[CamasM3e93]

Originally Posted by 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!

If it solved the problem to change the battery but returned later, did you register the new battery with the car's ECU?

[x Spades x]

If the problem went away, then came back, its either the alternator not maintaining the battery charge or battery registration kicking in.

[JaviV8]

Hello and thank you for your responses!

Yes, we registered the new battery when installed. I will comment anyway with my shop again.

Alternator, this was my feeling. But I messure 12,4 v in the battery with voltimeter, so apparently battery is charged enough.

This fail ONLY appears in when starting... and goes away if you lock down, wait two minutes, and restart.

I don´t know...

[RelaxIN2]

Subscribed...!!

[drwankel]

Exactly how did you register the battery?

[JaviV8]

Originally Posted by drwankel

Exactly how did you register the battery?

My mechanic explained to me that when batterty is replaced you “inform” the car with the OBD2 system. He did it and apparently was “confirmed”. Honestly I do not know more details...

However, the problem had appeared with old battery. So... not clear that new battery is the problem.

Well, patience. Some people with same problem recommended me to revise ground wire, I’ll do that and see.

Any clue is welcomed!

[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.

[Redd]

That ground strap can cause tons of weird issues. Always check the ground strap first.