[Resolved] Error Code U010100 - Lost Communication with Transmission Control Module (TCM)

[Kalleklovn]

I have a 2018 model 4motion. I got a fault code showing "Error Code U010100,Lost Communication with Transmission Control Module (TCM)", at the same time a fuse in the box located on the left side near the engine is blowing. See picture for witch fuse.

Has anyone had this error and can give me some advice on where to begin finding this fault, and what is the fuse for?

 

[Kalleklovn]

Fuse 5 in holder SB on left side in engine compartment is blowing when i turn ignition on.

 

[Dellmassive]

thats not good. . .

assuming its a DSG van with 4motion?

++++++++++

so the list is indicating the :

gear leaver solenoid,
the ign key solenoid
a DSG feed,

you would have to unplug each one in tern to locate which is the issue.


has anything happened just before the issue?

any work on the van?

any big puddles?

etc etc

++++++++++

T6 - Fuse Box layout map Box B

www.t6forum.com

 

[Kalleklovn]

It's a dsg gearbox. I had no warning before this happened. The car was working fine, the only fault i had was a faulty exhaust gas sensor that i was to replace next week. I went over a speed bump and suddenly the car would not drive forward but the engine was still running. Now the car thinks that the gear lever is in gear and it won't start. I will post the report from vcds with the latest faults.

 

[Kalleklovn]

Here is the print from vcds.

 

[Dellmassive]

went over a bump eh . . . . thats what started it?

weve had strange things like this before from @Bigsidavies

......


so possible electrical issues,

rubbed through cable for DSG?

or, either solenoid?

 

[Dellmassive]

Here is the print from vcds.

ok, there's a lot of noise in that report,

now you have that as a copy to refer back to.

delete all the codes,


and run a new scan to see what comes back.

 

[Kalleklovn]

Well... I'm not saying that the bump was the cause of the fault, just trying to paint the picture so i can get help to solve the problem. If i was driving on a straight road i would have said that to without indicating that the road was to blame.

 

[Pauly]

I would check all the wiring underneath in particular around and up to the mechatronic unit

 

[Bigsidavies]

went over a bump eh . . . . thats what started it?

weve had strange things like this before from @Bigsidavies

......


so possible electrical issues,

rubbed through cable for DSG?

or, either solenoid?

Yeah mine was a loose body earth. Was very loose so must have been like that for a while. The bump obviously moved the ring connectors and that was enough.

 

[Bigsidavies]

Well... I'm not saying that the bump was the cause of the fault, just trying to paint the picture so i can get help to solve the problem. If i was driving on a straight road i would have said that to without indicating that the road was to blame.

Non doubt the bump was the catalyst to make an existing problem show itself.

 

[Kalleklovn]

Yeah mine was a loose body earth. Was very loose so must have been like that for a while. The bump obviously moved the ring connectors and that was enough.

Do you remember where the loose connector is on the car?

 

[Kalleklovn]

I have disconnected the cable to the mechatronic unit and still blowing fuse number 5

 

[n10n]

I have disconnected the cable to the mechatronic unit and still blowing fuse number 5

Sounds like bit of good news - ofc the actual short still needs to be found but probably mechatronic would have been hugely expensive

 

[Bigsidavies]

Do you remember where the loose connector is on the car?

Mine was on the cab floor under the dashboard, but it didn’t throw up any of the errors that you have. No doubt something has become loose/damaged and the bump finally dislodged it.

 

[Dav-Tec]

Sounds like bit of good news - ofc the actual short still needs to be found but probably mechatronic would have been hugely expensive

A new mechatronic units is around £2700 plus seals, gaskets, oil, fitting etc so not much change from £4k when done

 

[Dav-Tec]

I'd personally disconnect the other 2 components first to isolate where to start before chasing wiring fault the bump has a clean scan been done yet

 

[Kalleklovn]

I have disconnected the cable to the dsg gearbox, the cable on the side of the gear lever and the cable to ignition key. Is this the right cables? In the fuse diagram for number 5 is running the selector lever, mechatronic unit and ignition key withdrawal lock solenoid.
With all cables disconnected fuse number 5 still gets blown.

The car was all good before this happened with only one fault code for the exhaust gas sensor. No leaks no other errors and the car has only been driven 160.000 km.

 

[Kalleklovn]

An update on this fault. Today i took out the cable to the lock solenoid an put it back again before attaching the battery, and the car starts. But while the car is running, the number 5 fuse gets blown, not as before when the fuse gets blown when only turning on ignition.

I still cannot get the car in gear, even when the fuse is ok before i start the engine.

 

[n10n]

• The fuse that's tripping is SB5, 15A
• It connects to mechatronic, selector lever and ignition key withdrawal solenoid (two diagrams are linked by the green box)
• There's no other connections to B488 connection point. B488 itself is somewhere within the loom, not at any connector or easy access spot.
• You have disconnected likely the correct plugs from mechatronic and selector lever but the power goes to N376 and from there to F319 which I believe is again in selector lever assembly. I could not find the fitting location of the N376 solenoid - but it's a solenoid so the two wires is all it has
• Considering above, I find it most likely to have a short to ground somewhere in red/yellow wire from SB5
• If you have a multimeter remove fuse SB5 and measure resistance from it's red/yellow to chassis with plugs and preferably battery disconnected (should be high/infinite but most likely is low/zero)
• Beyond that I think it's just awkward work to trace the red/yellow wire and find the problem spot. Or alternately run a new wiring - temporary wire run outside from bay to mechatronic and selector lever just might get you to switch to P. Have to locate that N376 as well though.