[richas]

I have these two persistent faults:

00C908 JBE: K-CAN line fault
00D904 CAS K-CAN line fault

I am not sure what BMW means by "line fault", is this a dropped or corrupted CAN frame?

Are these likely to be bad connections? Perhaps in the same connector? (Dare to dream)

Thanks

Rich

[gbalthrop]

Originally Posted by richas

I have these two persistent faults:
00C908 JBE: K-CAN line fault
00D904 CAS K-CAN line fault
I am not sure what BMW means by "line fault", is this a dropped or corrupted CAN frame?

I'm NOT sure what you mean by "a dropped or corrupted CAN frame".
Attached are ISTA ScreenPrints of the following:
1) Bus Diagnosis FTD (Vehicle Technical Diagnosis), page 1
2) Location of CAS & CAS Connector X13376
3) X13376 Connector View, identifying location of K-CAN pins #26 & #35.

I have NOT used ISTA to diagnose a Bus Fault. If you had ISTA, it would make diagnosis of an INTERMITTENT fault easier, per attachment 1.
You don't indicate if:
(a) the two faults you list are the ONLY communication faults in any module;
(b) if either or both of the two listed faults are intermittent, and if so, under what circumstances they appear;
(c) if there are any warning lights or performance issues/ symptoms which accompany either fault.

The X13376 K-CAN connection diagram, Location, and Connector View are attached to help you identify ONE possible location
of "Line Fault" in the K-CAN bus, namely pins #26 & #35 at Connector X13376 at the CAS Module. If you have NO CAS
Module Function that is lost, the first likely source of an intermittent K-CAN fault appears to be corrosion or other issue at one of
those two pins/sockets. Please let us know what you find,
George

[richas]

George,
Thank you so much for the help. Those two faults are the only ones present, I randomly checked my fault status so I do not know how long they have been there. There are no symptoms that I notice.
I do have ISTA and I will run the diagnostics below and I can explore the condition of the connector you mention and apply some contact cleaner.
Question: Should I disconnect the battery before unplugging connectors from modules? (They don't support hot-swap) I am always hesitant to disconnect the battery after reading about FRM module failures...

Rich

[Andystobbs]

Without an oscilloscope you might as well give up.

[richas]

Originally Posted by Andystobbs

Without an oscilloscope you might as well give up.

I have several oscilloscopes and I am certainly going to try to avoid using them.

[gbalthrop]

Originally Posted by richas

... I do not know how long they have been there. There are no symptoms that I notice. I do have ISTA and I will run the diagnostics below and I can explore the condition of the connector you mention and apply some contact cleaner. Question: Should I disconnect the battery before unplugging connectors from modules?...

Hi Rich,
1) If you still have fault code present (have NOT cleared it), using ISTA, click on Fault Code in "Fault Memory" list, and you will see two Tabs (sometimes ;-):
1) Description (NOT always present), and 2) Details; click on Details Tab and you should see the "mileage/km" per Odometer as of time the Fault Code was saved in Fault Memory. ALSO, at the top-left of screen under "Fault types", you should see either "Fault currently not present", OR "Faulty" if Fault is NOW present.
2) If you still have the fault shown in fault memory (whether now present or not), if you simply select a fault (if more than one), and then click "Calculate test plan" at bottom-right of screen, you will get a "Guided Tour"/ Directed Troubleshooting/ Trail of Breadcrumbs, directing HOW to diagnose the issue. That SHOULD take you through the Test Module described in the "Bus Diagnosis" attachment to earlier post. If it does NOT, then just follow the selection sequence stated in that attachment.

Before removing the CAS Connector X13376, I would simply pull the 2 fuses that supply power to the CAS Module: F36 (40A) and F55 (5A), BOTH of which are Unswitched Battery power.

Since there are NO symptoms or warning lights, if all else fails, just clear the codes and check back every month or two to see if there was a recurrence. I assume you are using ISTA > Read Out Vehicle Data > Complete Identification > Display Fault Memory? That shows ALL faults in ALL modules.

Please let us know what you find,
George

[Andystobbs]

Originally Posted by richas

I have several oscilloscopes and I am certainly going to try to avoid using them.

Why avoid using the best tool for the job? You could see the waveform in an instant and make a much better determination.

[richas]

Originally Posted by Andystobbs

Why avoid using the best tool for the job? You could see the waveform in an instant and make a much better determination.

You are making me come clean, well ok.

Laziness.

I often come to places like this with a problem like " I have a couple error codes" and what I truly want is a quick answer like, "Oh those, that is a well known thing, shoot some de-oxit on connector X on module Y". I like so many others here rely on George to teach us systematic debugging and show us how to use the tools, a Sisyphean task.

As an aging electrical engineer I have spent interminable hours debugging. I find that as I get older I am more and more happy to rely on the experience of others. I still enjoy a good mystery and the fulfillment of solving it, but it is balance between how much spare time I have (little) and the need for the problem to just go away.

So Yes! You are correct, a scope will surely give a picture of actual signal quality but that means locating the CAN H/L lines and splicing into them. (The biggest pain?)
I don't expect to see anything right away as this seems to be intermittent and has no other symptoms other than the com errors. I suspect there is a missed CAN frame counter that will trigger the fault after x misses and will invoke a pop-up message after x+n missed messages, which so far I haven't hit.
But I could hook up the scope to the CAN bus and wiggle connectors till I see noise.... But see laziness note above...

Rich

[Andystobbs]

I think a message that arrived improperly would more likely set a U code for missing message.

CAN H and L is everywhere on the car as you'll know and readily accessible at the CAS and JBE.

Though I know what you're saying, if it isn't broken don't try too hard to fix it.

[gbalthrop]

Originally Posted by Andystobbs

Why avoid using the best tool for the job?...

Originally Posted by richas

... rely on George to teach us systematic debugging and show us how to use the tools, a Sisyphean task...

There's NOTHING "Sisy"(phean) about using ISTA "Test Plan" to perform a "Flow Chart" type of test. I've never had a K-CAN "Line Fault" or used the ISTA Test Plan for anything like that, so I can't say if that's the "best tool for the job", or if an oscilloscope would do better.

My reading of the ISTA "FTD" ScreenPrint I provided earlier suggests to me that IF you have an intermittent "D904 CAS K-CAN Line Fault", ISTA MAY diagnose that quickly, if it does NOT, then try the oscilloscope, but I'm NOT sure where you would connect it, or if you can watch the scope as you drive, and HOW you will know when the wave form changes BEFORE you run into something.

If you're just looking for a "quick & dirty" (clean) way to do it, just pull the two CAS fuses, inspect/clean the two X13376 pins in question, reassemble, clear codes, and check for codes every two/three months (which you should probably do anyway ;-). I'm ALL FOR using the best tool for the job, and NOT spending more time than necessary in "Fixing" an issue. So since I have NOT used EITHER ISTA or an Oscilloscope to identify the cause of your issue:

We are waiting with "bated breath" (holding breath as opposed to eating sardines ;-), for your report of success & HOW it was achieved. Hope you survive the experiment.
George

[ezadel]

Hello.
Wondering if anyone has solved this or found a way to clear it. I have 00D904, 00E2C4, 00D204 KCAN line faults no issues except small battery drain ( battery will drain if car left a week). No other issues

[ptpending]

the use of the oscilloscope is best thing to troubleshoot can line
you connect them near every module in question and check if signal is conforms the pictures in ISTA
after that you can disconnect other modules except JBE, and check if signal become good, because JBE is master for all buses.

[ezadel]

Originally Posted by ptpending

the use of the oscilloscope is best thing to troubleshoot can line
you connect them near every module in question and check if signal is conforms the pictures in ISTA
after that you can disconnect other modules except JBE, and check if signal become good, because JBE is master for all buses.

Willing to do this do you have a guide somewhere on how to do it. I am not very electrically oriented.
For example what happens if the signal does not conform, what is the next step

Also where are those pictures on ISTA and what will oscilloscope produce?

[ptpending]

Originally Posted by ezadel

Willing to do this do you have a guide somewhere on how to do it. I am not very electrically oriented.
For example what happens if the signal does not conform, what is the next step

Also where are those pictures on ISTA and what will oscilloscope produce?

in your particular situation you have to check if any of your modules are water damaged
do your car has sunroof ?
do your car has hifi or harman kardon ?
do you car has pdc or comfort access (keyless) ?

[ezadel]

Originally Posted by ptpending

in your particular situation you have to check if any of your modules are water damaged
do your car has sunroof ?
do your car has hifi or harman kardon ?
do you car has pdc or comfort access (keyless) ?

Yes car has sunroof which does have some issues.. how can I take this further?
Also I noticed that the fuse for the cig lighter (12V) keeps blowing everytime my low tire pressure light comes on. Because of the cold and elevation change I get the low tire pressure light often and everytime the cig lighter fuse is blown and replaced

[ptpending]

Originally Posted by ezadel

Yes car has sunroof which does have some issues.. how can I take this further?
Also I noticed that the fuse for the cig lighter (12V) keeps blowing everytime my low tire pressure light comes on. Because of the cold and elevation change I get the low tire pressure light often and everytime the cig lighter fuse is blown and replaced

the sunroof has drains which used to pass the water to wheel archs
and since the water can be with some debrys, these drains become clogged and water spilling inside of the car and damage modules on can bus
us cars have separate TPMS ecu which is located between rear right wheel arch cover and body and rear bumper.
also the pdc and comfort access modules are located in the same side of the car, but inside, under the trim above battery
so you need to check this TPMS (RDC) module and modules above battery, if they water damaged

[richas]

This is an old post of mine but a whole bunch of K-can bus faults have popped up. I can’t clear them, ISTA shows them as present.

I’d like to hook up a scope to see what the bus activity looks like. Can someone recommend the easiest place to tap into this bus? Also, I am going to buy some Posi taps, anyone know what size to get?

Thank you
Rich.

[richas]

I’m gonna answer my own questions. It looks like I can get access to the bus at the wire bundles in front of the fuse block. I think the wire is around 22 gauge.

Rich

[gbalthrop]

Originally Posted by richas

... a whole bunch of K-can bus faults have popped up. I can’t clear them, ISTA shows them as present. I’d like to hook up a scope to see what the bus activity looks like. Can someone recommend the easiest place to tap into this bus? Also, I am going to buy some Posi taps, anyone know what size to get?

Hi Rich,
Can't help with your specific questions. NOT sure what a scope reading would show. While I believe in using technology, my initial approach would differ.

If the Fault Codes or functional issues/symptoms (if any, such as KOMBI "Light Show") began at SAME time, I would first want to know:
1) What electrical wiring/ connectors/ components were disturbed & where?
2) Has there been any water ingress causing wet floor/carpet in either footwell, particularly US driver side (left)?
3) WHAT are the "Message Errors" or CAN Bus Codes exactly? K-CAN bus, or others as well? View that Bus System in ISTA & identify connectors.
4) WHAT are the performance issues or symptoms exactly?
5) Then identify connectors in that Bus System, which MAY have gotten wet or corroded, & inspect them.

I have NO Idea if ISTA "Test Plan" offers tests to locate Bus Faults or NOT, but I would try that first. Please let us know what you find.
George

[gbalthrop]

Originally Posted by richas

... It looks like I can get access to the bus at the wire bundles in front of the fuse block...

If you're accessing K-CAN Bus, ISTA suggests X1716 is a likely suspect, BOTH for corrosion & easy Access.
George

[richas]

You’re amazing George,
Yes, I have had water ingress. Not In the driver’s foot well but in the passenger foot well on the driver side. My driveway is at a slight slope so perhaps it’s running down to that location but still hitting that connector.
There’s no outward indication of these errors, no check engine light or anything. I just ran a check randomly.

Here are the errors. I know about the roof related errors and the transfer case oil, I think that’s associated with X delete.

Sorry for the formatting.
Rich

Error memoryDate: 4/24/25, 8:44 AMVIN: WBAUU3C53AA540854
00
Junction Box electronics1 errorC908: K-CAN COMMUNICATION: WIRED OPERATION

01 Multiple restraint system1 errorC944: Bus line error - General

19 Transfer box1 error54C6: 54C6 oil wear

20 Tyre Pressure Monitor1 errorD104: Error CAN single-wire operation

40 Car Access System1 errorD904: KCAN__Leitungsfehler1

44 Sliding/tilting sunroof1 errorDA04: Error KCANLOW__

56 Function centre, roof1 errorA670: Error fitting sensor 0xA670

56 Function centre, roof1 errorA670: Error fitting sensor 0xA670

60 Instrument cluster1 errorE104: CAN LOW ERROR

63 Car Information Computer1 errorE1C4: K-CAN line fault

64 Park Distance Control1 errorE204: Error location: CAN low, physical bus error2

67 Controller (iDrive)1 errorE2C4: Bus line fault CAN

6D Seat module, driver1 errorE444: K-CAN: Bus line fault

72 Driver's side footwell module1 errorE584: Bus line fault K-CAN

73 Central Information Display1 errorE5C4: K-CAN error

78 Integrated automatic heating/air conditioning system1 errorE704: CAN-BUS. Physical bus error3

[richas]

George,
I cleaned X13376 and X1716, applying a bit of de-oxit and R&R’d the connectors a few times. No sign of moisture or corrosion that I could see.
Put it all back together and scanned for error codes. They also still seemed to be there, but I was able to clear them now, not something I could do before.

So no smoking gun, but fingers crossed.

Thank you for the help.
Rich