Gearbox malfunction message. DL501

[VinnysS4]

2015 S6 179,600 miles. DS1 stage 3, Srm turbos, downpipes, intakes and SRM TCU tune.
Haven't had any trans related issues since I've owned it. This morning it threw the gearbox malfunction message, along with Parking brake and TPMS error messages. No forward/reverse movement in any of the gears. Cooling fans on full blast.
Scanned with vcds and in the trans module I get a p0700 Control Module Defective. Most of the cars systems have codes for no communication with the TCU, along with "functions restricted due to missing message" (abs, instruments, airbags, etc)
I cleared the codes, no luck. Trans code comes back immediately. I cannot click on measuring blocks in the trans module as its grayed out.. Flashed from stage 2 to stage 3 with the DS1 to see if it did anything different.. no beans. Couldn't find a diagram listing a fuse or relay for the trans.
Where do I start?
Checking powers and grounds at the trans connector?
Is there a way to test the trans control module to see if it is infact defective?
Drop the pan and look for corrosion on the mechatronic unit?
Is this a common failure symptom/problem when the mechatronic fails?
Any help or insight would be very appreciated.
Thank you
Vinnyhttps://uploads.tapatalk-cdn.com/20221004/8afb01b867dca8a67c5d29879a78110b.jpg

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[Yeoman]

Common problems that trigger the P0700 Code:
Defective Shift Solenoids
Defective Engine Coolant Temperature Sensor
Defective Valve Body
Dirty transmission fluid that restricts the hydraulic passages

I'd start there..

[Botbasher]

I'd start there..

Don't forget how inter-connected these cars and systems are... is ANYTHING else out of sorts?

My buddies S4 went nuts one day. Christmas Tree Dash, Cooling Fans running full speed, TPMS, Parking Brake Fault, Limp Mode on the motor... a dozen DTCs!! He couldn't figure it out because it was telling him that almost every system in the car was F'd!!

After he played with it for an hour, I started looking at it. He sat there and lamented that "even the ambient sensor is reading 153F!" Wait, what? Why? So we go look at the sensor under the bumper.. a rock had hit it and damaged it. Hmmmmm I pulled mine off and stuck it in and now it read 84F... and the car cleared almost every DTC within seconds and the rest cleared and stayed gone.

So his "Cooling Fans full blast" reminded me that simple systems can effect big systems. It thought it was super hot ambient, so it was running all cooling fans, limiting power and warning the driver to knock off the stupid stuff!

Not that it's the same issue here, but don't overlook the simple problems (Why are cooling fans running for a trans code??) while you search for the big ones! Remember... our cars limit engine and trans operation when they think they are too hot.

Cheers,

KS

[Yeoman]

Don't forget how inter-connected these cars and systems are... is ANYTHING else out of sorts?

My buddies S4 went nuts one day. Christmas Tree Dash, Cooling Fans running full speed, TPMS, Parking Brake Fault, Limp Mode on the motor... a dozen DTCs!! He couldn't figure it out because it was telling him that almost every system in the car was F'd!!

After he played with it for an hour, I started looking at it. He sat there and lamented that "even the ambient sensor is reading 153F!" Wait, what? Why? So we go look at the sensor under the bumper.. a rock had hit it and damaged it. Hmmmmm I pulled mine off and stuck it in and now it read 84F... and the car cleared almost every DTC within seconds and the rest cleared and stayed gone.

So his "Cooling Fans full blast" reminded me that simple systems can effect big systems. It thought it was super hot ambient, so it was running all cooling fans, limiting power and warning the driver to knock off the stupid stuff!

Not that it's the same issue here, but don't overlook the simple problems (Why are cooling fans running for a trans code??) while you search for the big ones! Remember... our cars limit engine and trans operation when they think they are too hot.

Cheers,

KS

Hence the "Defective Engine Coolant Temperature Sensor"

[Botbasher]

Hence the "Defective Engine Coolant Temperature Sensor"

Correct... the point was to look at the whole of the car and ANY issues though, and not just the reported faults and expected solutions, as the Outside Ambient Temp Sensor tossed no codes but effected the entire car.

I was blown away by how many faults it created in "unrelated" systems with absolutely no obvious indicator of it's failure (I'm sure there was a soft code somewhere but we never found it) except for a value on the dash.

Cheers,

KS

[Yeoman]

Yeah it can get crazy..

[VinnysS4]

Common problems that trigger the P0700 Code:
Defective Shift Solenoids
Defective Engine Coolant Temperature Sensor
Defective Valve Body
Dirty transmission fluid that restricts the hydraulic passages

I'd start there..I appreciate the insight. I will dig deeper this weekend. I checked ambient air, coolant and a few other things. They were all within spec with outside temps. I will look closer at some more data pids.

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[flyfishing]

battery? cars give weird errors when battery sucks.

[nssf]

Have you inspected the transmission connector for corrosion?

[VinnysS4]

battery? cars give weird errors when battery sucks.Well I figured it could be the battery. 7 years old. High powered subwoofer amp in the trunk. Resting voltage was 11.5v. Too low. So today I picked up a new battery for her. Installed it. I was able to clear the codes with vcds and code the batteries BEM number Multiple restarts with no issues whatsoever. So I figured I would take her on a test drive. Made it about 3/4 mile away and bam. Christmas tree on the dash, car goes into neutral. Same thing. Just towed it home. Now the diagnosis begins...

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[VinnysS4]

Have you inspected the transmission connector for corrosion?No, thats the next thing on the list I'll be checking hopefully this weekend

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[VinnysS4]

Pulled the DSG plug and it was nice and clean. No corrosion. So I sprayed it with deoxit for good measure and reinstalled it. When it was cold I was able to put it in gear and pull it up on ramps, then able to park it afterwards. Had the car sitting at idle for a bit while I was messing with VCDS and I could hear a change in running when all the lights came on. The rpms changed and the fans came on.
I scanned the modules and the Engine control module threw a no Communication with Transmission code. The transmission module threw a new code. P179E Selector Lever Sensor: Electrical Malfunction

Other than a nice oil leak, everything looked normal. Nothing stood out to me underneath.
The rabbit hole deepens

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[VinnysS4]

Pics of DSG connector https://uploads.tapatalk-cdn.com/20221013/2fd574c6f048d372214582411bcb7f6e.jpghttps://uploads.tapatalk-cdn.com/20221013/8e87f1b82624db59f082d1557cf7bb80.jpg

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[VinnysS4]

Can anyone confirm something for me in their VCDS? In the Auto Trans module, the Measuring Blocks tab is grayed out. I'm curious if this is because of an actual No Com issue with my tcm or if its just normally grayed out. Can someone check this for me?

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[Afdj21]

Hi did you figure this out? Ive just had my OB5/DL501 gearbox out and replaced the clutch and rebuilt the Mechatronic unit. Went for the first start and it did all the thing you said.

[russjameson]

Hi did you figure this out? Ive just had my OB5/DL501 gearbox out and replaced the clutch and rebuilt the Mechatronic unit. Went for the first start and it did all the thing you said.

Ditto.
My transmission just crapped the bed on me too.
No transmission codes.
Multiple different Error reasons everything I try to adapt the clutch and valve body with VCDS. Throttle to high or low, speed to high or low( car isn't moving) car not in Neutral, ( I tried it in P and N)
I can't even do an output test on the shift lockout solenoid.

Car is just in neutral no matter what I select with the shifter. The RPMs change everything I switch to from R to N to D.

I'm stumped.

I'm trying to get my tuner that did my TCU tune to send me a plug flash my TCU back to stock. But I can't get ahold if him.