[silyb0y]

Hello fellow forum members!

I unfortunately have fault codes regarding the K-CAN. I can delete them with ISTA but they immediately show up again.

It started a few month back with just three control units (or mabye four?). As of yesterday seven control units showed fault codes regarding the K-CAN. All affected devices still seem to work just fine - however - I would like to sort things out because the the problem seems to be spreading...



Please note that it says "body can" next to FD2 - if I change the language to german it says K-CAN as with the rest of the fault codes.

I have checked the detailed wiring diagram of K-CAN in ISTA (SSP-BTS-SP0000052382) hoping to find a clue.
Problem is... I just dont get it - at all

If the ZGM itself reports a K-CAN problem... why are some of the units (on both K-CAN "branches") not affected while others are?

E.g. - the CID reports a K-CAN problem. The CID is connected to ZGM via X151*V1 and X151*V2 (high and low).
However - headunit, air condition, head up display share the same lines as above mentioned CID but dont report K-CAN problems at all.
Even more awkward -> the CID is the first unit in the line.

Or - the control modules of the rear entertainment monitors (FD1 and FD2) each share the same K-CAN lines as the corresponding seat modules.
The seat modules are allright but FD1 and FD2 report line faults.

I dont understand this at all. Are the incidents not related? Do I just have a bunch of defect modules?
Is it some other problem I havend thought of yet? How would you guys approach this?

[Twoone]

Do you have also other fault messages , voltage related?

Dit you do the ABL for busdiagnoses? (Activities > Function structure > 03 Body > System analyses > CAN functions > System analysis)



Problem could be:

1 Short in cable of K-Bus
2 Broken in cable of K-Bus
3 Fault in gateway ECU
4 Fault in Other ECU on K-Bus

Al units must "terminating" the bus with a resistor for correct impedance of the bus.

Note from ISTA doc: Diagnosis of intermittent faults and permanent faults
All cases where a data bus or control unit only fails temporarily (i.e. intermittently) are difficult for diagnosis. In such cases, the entries in the control units' fault memories do not point unambiguously to an intermittent failure of a particular data bus or control unit.

Intermittent failure of a particular data bus or control unit causes many different fault memory entries in several control units. The system analysis routine processes all of these DTC fault code entries (message missing) for all control units. In this process it employs a probability calculation to localise the fault cause within a specific sector.

If a data bus fails completely and permanently, the affected control units are no longer available for diagnosis. The fault is thus easy to locate.

[oceandiver86]

Did you measure the K-Can lines with a scope?
I guess one of the lines is faulty and now the system works in "limp" mode. and communicates on the other line.

common faults are water intrusion somewhere or a cable damage.
check the connection on the affected modules and unplug one by one until the scope pattern on both lines is fine again

[silyb0y]

Hi guys. Thank you for your replies!

I did have some fault codes regarding low voltage (I think 2x) last year.
But - Im pretty sure I caused them myself by watching TV in the car while waiting at the airport.
No voltage related fault codes since then.

I have not measured the CAN with a Scope yet (would have to borrow one). I will do the ABL for CAN as soon as I can - Ill report back.

Meanwhile... I did check for fault codes again today. Three fault codes (ZGM, VSW and seat module) were just gone (dont remember successfully clearing them last time). So - there were only four fault codes left - the same that I had last year (FD1, FD2, TRSVC and CID).



At one point (after clearing all fault codes) there was just one left (TRSVC).



Minutes later the three others popped up again - same as last year. I would say that thats an indication that the lines and modules (at least most of them) are actually OK right?

I wanted to pull the TRSVC module today - just to see what would happen. However - couldnt get past the trunk lid stop plates (special tool required)...

[rs@chip]

Which interface you use mate?icom or k-dcan or etc...

[silyb0y]

Which interface you use mate?icom or k-dcan or etc...

Hi Alex,

for my F01 I am currently using an Enet Interface.

[rs@chip]

Which interface you use mate?icom or k-dcan or etc...

Hi Alex,

for my F01 I am currently using an Enet Interface.

you can try with k-dcan and see if same dtcs are present..

[bm_tech]

Unplug the rear camera and re scan the car. take a screen dump and upload it.

then unplug the rear cam ecu and re scan, take again a screen dump and upload it.

[silyb0y]

Hi guys. Im sorry I didnt report back earlier. I was busy fixing the house - stuff was all over my garage... no space to work on my car.

@alex.eobd2:
K-dcan? I always thought that E-net was the only cable that works on F-series. Let me dig up my old K-dcan.

@bm_tech:
Will have to dissasemble my trunk-covers to get there.

[rs@chip]

Hi guys. Im sorry I didnt report back earlier. I was busy fixing the house - stuff was all over my garage... no space to work on my car.

@alex.eobd2:
K-dcan? I always thought that E-net was the only cable that works on F-series. Let me dig up my old K-dcan.

@bm_tech:
Will have to dissasemble my trunk-covers to get there.

yes it works if is good quality and change speed with k-dcan ulity..I told you that becouse once I got simular dtc codes as you..and second time with other tool dtcs was gone...