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Corrupt Canbus, xemodex said good luck

Help, Advice, Owners' Discussion and DIY Tutorials on the Volvo S80 model. Sometimes called an "executive car", the S80 was and continues to be Volvo's top-of-the-line passenger car.
imac
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Corrupt Canbus, xemodex said good luck

Post by imac » Tue Nov 26, 2019 2:36 pm

Hello, anybody have any ideas? 99 s80 T6, BRAKE FAIL STOP ASAP message start appearing for no apparent reason, and with increased frequency. Sometimes its fine for hours, other times its as soon as I turn the key it fails. Shift solenoid goes nuts, gear selector light stays in P regardless of gear, misfires, guages go dead except for fuel level, etc etc. All the fun volvo stuff.

Replaced battery with new, cleaned and di greased every ground I could find from trunk to engine bay, no change.
Cut open ABS module and resoldered, no change.
Replaced ABS module with one from wrecker same STC, no change.
Cleaned and di-greased all the canbus modules, including tcm, ecm, etm, no change.
Opened up the DIM to check for cold solder, no change.
Sent CEM and ECM to xemodex, they sent them back saying they both checked out fine and good luck.

Bought a cheapo oscilloscope and tapped channel A into CAN H and channel B into CAN L with both referencing ground. The network looks good,
Good bus.jpg
until for no rhyme or reason, the BRAKE FAIL message appears on the DIM, and the network goes haywire.
Bad bus.jpg
When the network is in a fail state, Vida codes show a slew of CEM, DDM, TCM, SRS, ABS faults.
When the network is in a good, non corrupted state I can clear down to:
CEM-1A59 Com w/ AUM control signal missing (I have an aftermarket stereo installed, so this makes sense)
DDM-0025 Mirror motor signal missing
SRS-0034 SIPS left front resistance high
SRS-00D1 Seat buckle, passenger signal missing
SRS-0115 Control module internal fault
SRS-E03 Configuration fault

Between the scope and the vida, how can I narrow down the culprit?

Thanks!
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RickHaleParker
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Re: Corrupt Canbus, xemodex said good luck

Post by RickHaleParker » Tue Nov 26, 2019 3:39 pm

The SRS-0115 & SRS-E03 has me wondering if the SRS module is talking out of turn.

You might take non-critical modules offline one at a time and see if you can isolate it to a module.


Platform: P80 1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package, Plant: Uddevalla Sweden.

Platform: X40 (Nedcar) 2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000. Plant: Born Netherlands.

Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0,
Plant Torslanda Sweden.
----------------------------------------------------------------
1997 S90, B6304S, AW30-42, Bosch Motronic 4.4 - Sold

imac
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Re: Corrupt Canbus, xemodex said good luck

Post by imac » Tue Nov 26, 2019 4:04 pm

If I probe the green and white wires (can high and low) at the cem, and unplug modules one at a time, will the network clear right away or will the cem latch onto a corrupt network and stay that way regardless of if the damaged module is still physically connected or not?

Is the canbus network is physically wired as per the map in vida?
Nov26.jpg
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Re: Corrupt Canbus, xemodex said good luck

Post by RickHaleParker » Tue Nov 26, 2019 7:08 pm

Yes the network is wired up that way.
Where are you taping CAN H and CAN L? There is more then one CAN H and CAN L buss.

Another thought: You are electrical as the datum. What you are seeing maybe power supply noise which can wreak havoc on the whole network. Next time you have it in fault mode, move the probe to the B+ and check for power supply noise, which could be as simple as dirty battery terminal, defective connections to Alternator voltage regulator going out.


Platform: P80 1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package, Plant: Uddevalla Sweden.

Platform: X40 (Nedcar) 2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000. Plant: Born Netherlands.

Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0,
Plant Torslanda Sweden.
----------------------------------------------------------------
1997 S90, B6304S, AW30-42, Bosch Motronic 4.4 - Sold

imac
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Re: Corrupt Canbus, xemodex said good luck

Post by imac » Tue Nov 26, 2019 8:55 pm

Thanks for the feedback Rick, much appreciated. Currently I am tapped into the CanBus network at the AUM plug. My next step is to tap into the canbus as close to the CEM as possible and start unplugging modules from front to back while watching my oscilloscope at any hint of the network recovering. I'm having trouble finding a complete data wiring diagram from a 99 s80, my vida dice software contains no wiring diagrams at all.

When you say test B+, are you referring to the + on the battery? Thanks again



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Re: Corrupt Canbus, xemodex said good luck

Post by RickHaleParker » Tue Nov 26, 2019 10:15 pm

B+ is the wire from the Alternator (+) to the Battery (+).

Look at the wiring diagram for the Data Communication below.
See the two sets of High and Low CAN bus attached to the CEM.
There is a 5th CAN bus from CEM pin D:6 to the ECM & TCM.
There is a 6th CAN bus from CEM pin A:18 to the LSM.
There are more CAN buses other then the 6 listed above.

The Electrical Wiring Diagram (EWD) for the 1999 S80 is Volvo TP3939202, Google it, there is a free downloadable copy out there.
DataComm_Page_1.jpg
DataComm_Page_2.jpg
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Platform: P80 1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package, Plant: Uddevalla Sweden.

Platform: X40 (Nedcar) 2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000. Plant: Born Netherlands.

Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0,
Plant Torslanda Sweden.
----------------------------------------------------------------
1997 S90, B6304S, AW30-42, Bosch Motronic 4.4 - Sold

imac
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imac

Re: Corrupt Canbus, xemodex said good luck

Post by imac » Wed Nov 27, 2019 8:13 am

I sourced a TP3939202 pdf, that's exactly what I needed, thank you.

Looking at the drawings, I am currently on the lo speed bus when seeing this corruption. I'll swing the scope over to B+ this morning once it fails and see what the alternator is up to.

If a lo speed module fails, say the DDM, can it cause all this havoc on the hi speed bus as well, or are they electrically isolated?
That wraparound wire from D:6 on the CEM to B:22 on TCM (my s80 is auto trans) throws me right off as well... same as A:18



imac
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Re: Corrupt Canbus, xemodex said good luck

Post by imac » Wed Nov 27, 2019 9:37 am

Ok, car has been sitting overnight, it started fine but within seconds BRAKE FAIL appeared.

I put the scope on the CANH side of the LO SPEED bus via the AUM plug, and the familiar corrupted waveform was shown. I swung channel A from the oscilloscope onto the positive battery post under the hood (which comes from the alternator, on its way to the battery in the trunk) and it looks rather stable, both probes are on 1.0v on the scope, (Channel B is CANH on LO SPEED at AUM):
B+ vs CANH lo speed.jpg


Here is a close up of the B+ only at 0.2v divisions:
B+.jpg
Using a fluke multimeter a 14.1vdc is shown constant.
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Re: Corrupt Canbus, xemodex said good luck

Post by SuperHerman » Wed Nov 27, 2019 11:01 am

I am throwing this out with really no clue, other than your problem is very odd.

Try unhooking the alternator or focusing on it. Maybe you are getting a dirty feed as it appears to be the only common. First I was thinking it was heat related, but not when it starts right away per your last post.

If you take the alternator out of the equation you can eliminate it as a possible source.



imac
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Re: Corrupt Canbus, xemodex said good luck

Post by imac » Wed Nov 27, 2019 12:16 pm

Again, thank you for the replies, it's much appreciated!

I will try disconnecting the alternator next, it has started pouring rain here so that's a tomorrow job. My only issue with the alternator being the cause is after the network has crashed, I can shut the car off (scope still shows corrupted canbus via AUM port) disconnect the battery, short out the chassis ground to battery +, reconnect the battery, turn the key to ON (not started) and the scope will show the network is still trashed. That, to me, doesn't sound like the alternator being the culprit, but anything is worth a shot !

Using the wiring diagrams (thanks RickHaleParker) I traced out the junction point 53/435 - 53/436 and soldered over the mechanical crimp, no change.
Soldered.jpg
I cannot find this physical joint on the high speed bus though, between the CEM and the ABS module 53/353 - 53/352.... does anybody know where to look for this? Which side of the firewall does it hide?
Where are these.jpg
Since I had the CEM down and out I figured I'd pop it open and look for any physical water damage or a cold solder on the connector pins,
CEM.jpg
there was nothing obvious so I put it all back together and reconnected the battery. The network stayed true for a few minutes then started peaking out again. While driving and watching the scope, it cleared up after a few minutes so I pulled over and restarted the car, it was fine for a few minutes then got garbled yet again. It's odd that the network was able to recover but then crap out again mid-flight.

Hmmm.....

I've read that canbus has 120ohm resistors as end of lines. Is that integral to the ETM on the high speed side? Is it measurable with an ohm meter? Thanks all, this is frustrating and winter is coming quick
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