No comms to radio & can-bus single wire.

[greg123]

I'm slowly resolving issues but these are happening all the time now (they were not there a few weeks ago - no work done to car/anything disturbed). I regularly see radio communication intermittant issues, clear them and they go away for a year usually, software fits I think. But this is all the time now, eg I can scan it, clear it, scan it - it's back.

Everything works though, including being able to scan the radio and the radio getting louder as I go faster, full radio function etc. All doors/locks work. Instruments fine. But something somewhere is causing this. I even tried disconnecting the battery & shorting out the car + and - for 5 mins to reboot all the ecu's and kill any short term memory, no improvement. The rear left door fault takes a few days to come back, unlike the can-bus and radio comms which are always there now.

Any thoughts or more tests I can do appreciated. My speedo issue seems to have gone, I hope, now I replaced the speedo sensor after changing diff oil in the 01M box. Incidentally the oil was low and horrible, looked like slimy black grease with lots of black sediment, the car is now quieter too - no trans noise.

Greg.

Address 17: Instruments Labels: None

Part No: 1U0 920 921 H

Component: KOMBI+WEGFAHRSP VDO V08

Coding: 31412

Shop #: WSC 31480

TMBFL21U638669636 SKZ7Z0B1375544

2 Faults Found:

01336 - Data Bus for Comfort System

80-10 - Single-Wire Operation - Intermittent

01304 - Radio

49-00 - No Communications

-------------------------------------------------------------------------------

Address 19: CAN Gateway Labels: 6N0-909-901.LBL

Part No: 6N0 909 901

Component: Gateway K<->CAN 0001

Coding: 00006

Shop #: WSC 31480

3 Faults Found:

01336 - Data Bus for Comfort System

80-10 - Single-Wire Operation - Intermittent

01304 - Radio

49-00 - No Communications

01333 - Door Control Module; Rear Left (J388)

49-10 - No Communications - Intermittent

-------------------------------------------------------------------------------

Address 29: Left Light Labels: None

Part No: 1U0 941 651

Component: EVG GDL + AutoLWR 0002

Coding: 00005

Shop #: WSC 31480

2 Faults Found:

01539 - Headlights Not Adjusted

35-00 - -

65535 - Internal Control Module Memory Error

00-00 - -

-------------------------------------------------------------------------------

Address 46: Central Conv. Labels: 1C0-959-799.LBL

Part No: 1C0 959 799 B

Component: 4Q Komfortgerát HLO 0003

Coding: 00259

Shop #: WSC 31480

Part No: 1U6959802D

Component: 4Q Tõrsteuer.FS KLO 0004

Part No: 1U6959801D

Component: 4Q Tõrsteuer.BF KLO 0004

Part No: 1U0959811D

Component: 4Q Tõrsteuer.HL KLO 0004

Part No: 1U0959812D

Component: 4Q Tõrsteuer.HR KLO 0004

1 Fault Found:

01336 - Data Bus for Comfort System

80-00 - Single-Wire Operation

[Tech1e]

Couple of different faults there I think.

Have you changed the left hand rear window motor? I think thats knocking out the can comfort system. A simple wiring check back to the gateway would verify this, although it is an intermittant issue.

Headlights arent set properly, can you set them up? An internal check sum error fault usually means a faulty ECU though, see if that clears at all, if not a new ECU is on the cards unless you can flash it.

The CDL fault is just showing that the comfort system is in single wire mode due to a faulty headunit I would think.

But however multiple can faults could indicate a faulty gateway ecu.

[greg123]

Hi - thanks for the reply. I'm learning can bus so it's not my area of experience.

Not changed/touched ANYTHING on the comfort system. The LHR door and window work perfectly. I can do a continuity check but what would I be going from/to? Also is there a way to disconnect and check the flexibe section leading into the door, would this be a likely break area?

The radio works perfectly, can it do this and have a fault causing no comms with instruments/can bus? The cd player is missing so I re-coded it to 'no cd player installed' to get rid of the 'cd player no comms' error, but that was before this. Could I have caused an issue there?

Also, how come I can scan the radio fine via vagcom, but the instruments and canbus can't talk to it. Doesn't it all talk through the same bus or am I logging into it via vagcom on k line?

I guess I can make a start by pulling the radio and seeing if the single wire issue goes away? If it doesn't, I guess I'll need to look around the rear left door wiring for a break which I'm not sure what wires to look at yet.

Finally the lights - I'm awaiting fixing the front height compensator, then will adjust them. They work just fine, and level, the ECU error only occured since I had them out to replace blown bulbs (not the xenon ones) so I'm not sure what could have caused it. If it doesn't cause an issue once I fixed the front height compensator, I'm tempted to forget that one unless anyone knows how to flash the ecu/reboot it.

Greg.

Couple of different faults there I think.

Have you changed the left hand rear window motor? I think thats knocking out the can comfort system. A simple wiring check back to the gateway would verify this, although it is an intermittant issue.

Headlights arent set properly, can you set them up? An internal check sum error fault usually means a faulty ECU though, see if that clears at all, if not a new ECU is on the cards unless you can flash it.

The CDL fault is just showing that the comfort system is in single wire mode due to a faulty headunit I would think.

But however multiple can faults could indicate a faulty gateway ecu.

[greg123]

Just done a bit more research and on the ross-tech site, it says that only the double din highline radios on the newer vehicles have can high/low connectors, the older radios like mine just have k line connector. Are they wrong, if no can connector how can it cause the can bus single wire issue?

Greg.

[greg123]

Okay I have some more information. I went into the can-controller, measuring block 130. There I saw the status switching from 1 wire to 2 wire and back to 1 wire constantly, about once or twice a second. I then looked at all the can status for the modules (rear door left, abs, gearbox etc) and all of them were '1' (status okay) other than the radio which was status '0' (status bad). Also the optical link status was 1 wire too. So, I pulled the radio out and disconnected it. I then went back and checked - nothing different. Canbus still flicking from 1 to 2 to 1 wire status, optical still on 1 wire. Radio still '0' obviously, as it was out.

So, I put the radio back in. I then disconnected the left rear door connector to the b pillar. This had an immediate effect when I reviewed, the canbus status was solid 2 wire now, the single wire operation fault was gone and the optical status was 2 wire too. HOWEVER, the radio still showed status '0' and canbus and instruments still showed error 'cannot communicate with radio'. Also, intermittantly if I logged into the can bus or the instruments with the side lights or brake lights on, it still brings up a beep and 'lights failure' warning on the dash, though it does not generate a fault in vag-com. I cannot fathom that.

I then plugged the door back in, to my surprise the 2 wire status stayed, the optical status remained 2- wire and so far the single wire operation fault has not come back. I wiggled the wires etc and couldn't get it to go faulty again, so far. I'm not sure why this would be, the connector was in perfect conditon. I will re-scan again later after a run on the road. However the rear left door no communications - intermittant error came back pretty quick. Even though when I'm viewing the can status for the rear doors while working the door, wiggling the wiring, operating the locks and windows it stays at '1' can status okay.

What to do next? That's the question.

Greg.

__________________

[Tech1e]

Can works just fine in single wire mode thats why you still have diagnostics.

[greg123]

I'd just like to get rid of all the errors and have a clean vagcom scan. Plus, I still have the speedo issue where the speedo needle drops out over 80mph and I wanted to clear these faults off first (already replaced the speedo sensor, no associated faults when scanned).

Faults just bug me, even if they only show up in scans ;-)