2013 - C7 A6 Allroad - 03157 - Functionality limited due to Communications Disruption

   #21  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
So I got the radio removed without drama and verified a few things:

1 - perfectly good electrical connection from the green/purple drag wire back to the CAN gateway under the rear seat

2 - with the optical connector unplugged (and ignition ON) I do see light signal (from gateway)

3 - no VCDS connectivity with radio (5F) while optical connector was unplugged (unless some general comms stop when LOS is detected)

4 - also had a look at all the red engineering menus on the unit - did not alter anything and it doesn't look like you can anyway - nothing immediately useful there for mere mortal DIY folk - I will post some pics for posterity though as this RMC animal seems to be not very well documented in the Audi owner forums (not that I can find anyway)

Next up will be removing the cluster (and half the dashboard trim along the way to get the stupid thing out by the looks of it). Need to verify that pesky green/purple diagrams wire has a good connection with the gateway.
 
   #22  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
Light from the gateway confirmed while Ignition ON - but it times out after little while - normal

IMG_1893.jpg
 
   #23  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
And the OBD diag wire...

IMG_1889.jpg


And the front view...
IMG_1890.jpg
 
   #24  
   #25  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
Before I start removing the cluster I got to wondering about the LWR/AHLS/J431 unit itself - it took a few attempts to get an acceptable coding value loaded on that unit, but the car had no such nagging comms errors before I fitted that unit. I needed to fit it so I could get basic settings for the bixenon lamps done to point them correctly on a beam alignment gauge. I cannot help wonder if some coding mismatch between that (and BCM, or cluster or radio) is the root cause.

I am thinking to unplug the fuse for J431 (see it cannot send any messages on extended CAN bus), disable/unselect it from the CAN gateway and code out any mention of LWR/AHLS in the BCM and cluster (taking me back to the coding before I added it) and see what that brings. Its certainly less time consuming than all the trim removal - if I still have issues on that configuration then its worth while checking the OBD diag wire is present and correct at the cluster... I want to remove the J431 variable basically as I cannot trust the coding.
 
   #26  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
So I have reset all coding back to where it was last good with bixenons fitted and J431 not active (fuse removed). I even swapped back the original CAN gateway which has no support for extended CAN Bus used by J431/LWR/AHLS. Comms error on RMC & instruments still there (despite clearing multiple times and ignition on/off etc)... leaves me with no other path but to pull the cluster.
 
Last edited:
   #27  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
Right now riddle me this - cluster removed without drama - there is no optical connectivity anywhere near it - my hand was well stuck behind that hole hoping to find it but nope - not ever fitted. With ignition on I get MOST light at CAN, RMC and BOSE connectors which means the MOST loop is perfectly in tact - its only VCDS that expects the instruments to have optical connection.

IMG_1909.jpg
 
   #28  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
The cluster itself does have the expected MOST optical plug of course...

IMG_1910.jpg
 
   #29  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
Oh and no sign of the now infamous green/purple OBD diagrams wire - which goes to show the Audi factory schematics cannot be trusted - not for UK/RHD vehicles anyway... unless there is a specific variant of diagrams that I cannot find.

IMG_1913.jpg


IMG_1912.jpg
 
   #30  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
So given all coding is back to EXACTLY where it was before the CAN g/w with extended bus was first attached to the car:

Q1 - has the new gateway somehow changed some adaptation values on the cluster or the RMC unit where it expects to see MOST connectivity at the cluster ?

Q2 - is this error code about optical comms problems on the radio a complete red herring invented by VCDS because it somehow assumes that there should be MOST optical connection to the cluster ?

Q3 - is there a way to configure VCDS (or coding or adaptation channels) on the car to tell it not to expect MOST optical connection at the cluster ?
 
   #31  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
So now I am really wishing I had saved admaps & block maps on the whole dang car before connecting this other CAN g/w.
 
   #32  

Uwe

Benevolent Dictator
Administrator
Joined
Jan 29, 2014
Messages
48,902
Reaction score
33,626
Location
USA
VCDS Serial number
HC100001
Q1 - has the new gateway somehow changed some adaptation values on the cluster or the RMC unit where it expects to see MOST connectivity at the cluster ?
I don't think that's possible, but can't rule it entirely.

Q2 - is this error code about optical comms problems on the radio a complete red herring invented by VCDS
VCDS reports what the car has to say.

Q3 - is there a way to configure VCDS (or coding or adaptation channels) on the car to tell it not to expect MOST optical connection at the cluster ?
Nothing obvious I've found.

At this point, I suspect the higher-spec gateway is supposed to be matched with a cluster that has a MOST connection, although it's quite curious that the gateway itself isn't showing a fault, while the Infotainment is.

-Uwe-
 
   #33  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
Yeah the real brain-ache is why the comms error persists with the original gateway and all codings identical to when it was error free. At that stage the BCM changes had been done for the bixenon conversion.

Somehow when the dealer removed CP on the "new" gateway (to activate extended CAN bus for J431) this comms error crept in. It's my own stupid fault for only saving code values - I know now that I should have saved all the admaps etc for the car.
 
   #34  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
Never did get to the root cause on this one but somehow the car is configured to expect it to have MOST connectivity to the instrument cluster. What it actually has on the MOST connection is CAN --> RMC --> BOSE --> (back to CAN).

So when you do an AUTO-SCAN it tries to contact the cluster ($17) on MOST (which it fails to do) and RMC ($5F) has the nag alarm about lack of comms to cluster.

When you select instruments directly from VCDS it connects over regular CAN and reports no issues.

All very odd and tedious - have refitted the 'new' gateway and coded LWR/AHLS ($55) back into play - the fault situation is no different with or without it.
 
   #35  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
So now I am really wishing I had saved admaps & block maps on the whole dang car before connecting this other CAN g/w.
Turns out... I did (well most of it) :o

Was one of the first things I did as new VCDS user so wasn't so clued into it - this was before the xenon retrofit and new CAN module. I happened to find them saved in a dark corner of a laptop.

I saved a mix of PLA, PLB and CSV files for BCM ($09), RMC ($5F), CCM ($46) and ICM ($17). The CSV file structure is half way user friendly but at least now I have a chance to find some difference lurking in there.

Think I will have to investigate RMC ($5F) first of all.
 
   #36  

Uwe

Benevolent Dictator
Administrator
Joined
Jan 29, 2014
Messages
48,902
Reaction score
33,626
Location
USA
VCDS Serial number
HC100001
   #37  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
Yes I plan to "diff" them but I did already eyeball some small differences in RMC admaps- is there any documented channels ?
 
   #38  

nugentp

Verified VCDS User
Verified
Joined
Jan 3, 2019
Messages
391
Reaction score
209
Location
UK
VCDS Serial number
C?ID=353561
Posted the comparison here as an XLS file.
Any suggestions ?
 
Back
Top