Garages avoiding my Body Control Module fault (U0140) - affecting Start Stop

[AndyStripes]

Third unsuccessful visit to a garage so reaching out here in the hope someone can help.
In a nutshell, T6 2016, 100k miles, dash says Start Stop error but no other problems.
VW say "no comms with BCM or alternator. We think it's a break in the wire" but won't give me a price for fixing it.
Auto electrician #1 says "alternator is kicking zeros. Should be 1's and 0's".
Auto electrician #2 did a quick diagnostics report. Fault U140 00 047 - no communications with BCM. Frequency = 163. Also EGR sensor 1 (Fault P046C 00 108) Implausible signal. No mention of alternator on the full print out! He says a break in the wire in highly unlikely, the codes don't suggest that and VW just wont want to touch it, hence why I'm being fobbed off.

I'm about to convert the van but am nervous about installing a leisure battery with CTEC etc if the electrics are dodgy. Any pointers to help me would be really appreciated.

 

[Dellmassive]

you need a decent VAG auto electrician/diagnostics guy to look at it that has VCDS or a decent scanner and scope.
stop/start is a very complex system, so any error/problem in any of the associated systems will cause it to stop working.
the problem could be as simple as an unplugged or corroded connector.
possibly a rubbed through a wire . .
The "BCM - no comms" may be the likely direction to go.
The EGR code more likely not part of it.
possibly just a faulty battery current sensor/ or unplugged battery sensor?

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DATA:
I'd start by doing a full module scan, to make sure all modules are present.
then a full code scan for fault codes,
then start looking at PID`s.
the start looking at all the PID`s that relate to the stop/start etc.
the codes will most likely give a general direction.
The alternator has a LIN bus connection, data bus readouts via VCDS. etc.
check alternator connections to ECM / BCM.

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electrical:
drop test the battery . . . is it charged?
voltmeter test the battery and alternator - is it charging?
have you had a flat battery?
is the electrical/charging system working?
if so, then look at other stop/start required inputs.

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more info:

T6 TPI - Start-stop System Fails Intermittently, Engine Does Not Switch Off Or On -

Being a T6 geek and spending my Sunday afternoon trawling through T6 TPI`s and Service info i thought i would share this with you. stop/start is a very complex system even though you would assume its simple. An interesting read IMO and details the stop/start requirements and issues/non-fault...

www.t6forum.com

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Dellmassive`s -- "how I Done It" -- Thread
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[Loz]

I wonder if its no comms with the battery shunt?

 

[Dellmassive]

LOL . . . @Loz literally just added edit: "possibly just a faulty battery current sensor/ or unplugged battery sensor? "

 

[Loz]

LOL . . . @Loz literally just added edit: "possibly just a faulty battery current sensor/ or unplugged battery sensor? "

yes and a cheap thing to swap to start with..

 

[AndyStripes]

Arhh... you might be onto something. So the wires coming out of the battery monitoring control unit have been fiddled with. The copper has been exposed, our guess is the previous owner wanted to probe the wires. The wires arn't touching each other tho, but could have shorted. But I would have thought that this did this because there was an existing problem? Thanks for such a great response tho - much better service than VW!

 

[2017transportert6]

hello everyone, just been looking through the forums and I have EXACTLY this fault. was it ever resolved?

 

[2017transportert6]

Has anybody made any progress with this fault?? it's still causing me issues. local main dealers are useless and will keep my van for too long and then still not fix it!

 

[Dellmassive]

have you looked at all the suggestions above yet?

 

[Loz]

@AndyStripes ?

 

[Scotchkris]

Had this same issue with start/stop, it was the small cable within the loom from alternator to the battery module that was broken, apparently very common

 

[Bigc891]

I have a 2017 highline, and i have this exact problem, seems as though iv just bought someones else’s problems. The auto electrician says hes never seen this before but seems to think it could be something to do with the alternator??

 

[AndyStripes]

Hi guys, still no progress on this. I've done 30k since this post, and no other problems, other than the start-stop thing still persists!

 

[Bigc891]

Is your van fully standard? Surely vw have seen this problem before..

 

[Murdoch]

Interestingly my van has stopped doing the stop / start in the last few days - despite doing 500 miles over 2 days last week!

Anybody got a picture of the wire I need to look for?

thanks

 

[Jimmy-s3]

Had this same issue with start/stop, it was the small cable within the loom from alternator to the battery module that was broken, apparently very common

Hi, I’ve this same problem.
How did you go about fixing the wire?

 

[mmi]

Error code 02252 - Battery Generator - error stop start on dash

hello i have a 2017 transporter t32 shuttle and when i got it, it had a stop/start error code come up on the dashboard i read the fault codes and it has 2 that keep comming back 01 Engine Control Module 1 U014000 Lost Communication with Body Control Module 5F Information Control Unit 1...

www.t6forum.com

 

[Lightrofit]

I fix loads of these. Usual issue is water ingress sometimes coupled with ham fisted construction at factory or impact damage.

Here's one I did this week. Same symptoms: S/S error on dash, comms error code with no power output from alternator.

Cut out the bad and replace with a good length plus add extra protection from moisture and physical damage.

 

[Jimmy-s3]

I fix loads of these. Usual issue is water ingress sometimes coupled with ham fisted construction at factory or impact damage.

Here's one I did this week. Same symptoms: S/S error on dash, comms error code with no power output from alternator.

Cut out the bad and replace with a good length plus add extra protection from moisture and physical damage.

View attachment 186959

I’ve been under my van today and exposed that thin green/yellow Lin wire from the alternator plug.. I couldn’t really find a fault in the wire but I’d like to still replace it for a slightly thicker version and run it up to the battery monitor area to bypass most of the length.. just incase I’ve missed the break/fault in the wire..

 

[Jfoz]

My t6 was in the garage today for a few bits and this issue. My man did the wiring bypass but the issue still persists. Could it be the negative control unit on the battery? Or any other suggestions