508 CAN bus problem

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ketyow
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508 CAN bus problem

Post by ketyow »

Hello, the car is Peugeot 508, 2011, 2.0 163HP. After starting a car, sometimes immediately, sometimes after few minutes of driving a lot of faults appear - most of them about Intersystems CAN (communication fault with ESP ECU, One of parameters present in BSI datastream is invalid, Loss of communication with the ABS/ESP module, Speed of rotation of the steering wheel fail, Vehicle speed data fault, Fault absence of communication with ECU - and many others related to loss of communication with many car systems). I measured too high voltage values on CAN bus - CAN high has 3,25V while CAN low has 2,96V measured at ODB2 socket. Car goes in emergency mode, there is no ESP/ABS, no speed indication, sometimes the air condition is not working and automatic gearbox goes in emergency, only third gear available. If I will drive for a twenty minutes to heat engine, then stop the car, the CAN high voltage drops to more proper values (CAN high 2,68V, CAN low 2,39V), then I'm able to reset the faults and I can use a car for whole day without any problems. Next day in the morning same problems come back. Looks like the car is hot the faults go away.

Do you have any clues what could cause the problems? All "minus" connections to the ground were cleaned, fuses cleaned and checked, but still there is something causing problems with too high voltage on CAN bus and then car gets crazy. Battery is almost new and checked - ok. Charging and battery voltages - ok. Resistance on CAN bus measured at OBD socket - ok. No damaged cables found.

What module is responsible for giving a proper voltage on CAN? BSI? Or it might be any sensor damage that causes faults on communication?

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GiveMeABreak
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Re: 508 CAN bus problem

Post by GiveMeABreak »

Most of the ABS / ESP / Handbrake / Steering Wheel Angle faults are all related, as they are all handled by the ESP ECU.

Have you added any aftermarket equipment - changed the Head Unit / Radio / added some other kit at any time?
Have you been undertaking any work near the BSI / engine fuse boxes / supplies?
Have you had any work done on the brakes?

ketyow
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Re: 508 CAN bus problem

Post by ketyow »

"No" to all three questions. I used the car for the last 15.000 kilometers without any jobs done, without any faults ( i often check the car with FAP application). It happened suddenly two days in a row in a morning (after heating up engine and resetting faults car was used for whole day without problems, nothing unusual happened), then when it was really hot outside I had few days without faults. Then again faults occur - my car mechanic can't find a solution even with oscilloscope, but it's hard to find a guy who really specializes in french cars.

I thing that faults sometimes go further than only with ESP ECU, like "fault in the gearbox electrical control on CAN network", "flaps jammed shut or other failurs" (only once), "internal combustion engine status information missing".

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GiveMeABreak
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Re: 508 CAN bus problem

Post by GiveMeABreak »

If you put the ESP / steering / electronic handbrake errors aside for a moment what are the actual fault codes are you getting? List these up with your VIN and I'll see what the symptoms can be.

If there are multiple system failures, a common suspect is the engine fuse box / BSI or wiring loom that has breaks in the wiring. I'll have a better idea when we know the codes.

ketyow
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Re: 508 CAN bus problem

Post by ketyow »

VIN: VF3**************[VIN obfuscated, can be read by forum staff] (no electronic handbrake, no start/stop)

Faults:
U1308
U1108
U1218
U1113
U1208
U0122
U1105
U1318 (not always)

Other like steering wheel angle speed or vehicle speed mostly related to no communication with ESP ECU.

I'm wondering if a defective sensor or other equipments may cause some fluctuations on voltage that causes loses of communication. If it's problem BSI, BSM or ESP ECU - how to start diagnosis, which one is faulty?

ketyow
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Re: 508 CAN bus problem

Post by ketyow »

One more thing I have noticed is that turning a steering wheel is a little bit harder when faults occur. If there are no errors it works more slightly. But it's not a thing that could be noticed by someone who doesn't drive the car everyday. On FAP application voltages on pump were possible to check even with steering wheel angle error - normally around 8.5V AFAIR, raising when I turned a wheel, with a voltage of ~85V when hard to left or hard to right. Is it possible that loss of CAN communication can be a reason of (a little bit) harder operation of wheel? Or maybe there is a problem with power steering ECU and it causes problems with whole CAN bus?

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GiveMeABreak
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Re: 508 CAN bus problem

Post by GiveMeABreak »

Ok, thanks for this info - leave it with me and I'll take a look now.

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Re: 508 CAN bus problem

Post by GiveMeABreak »

Ok, one important question - have you attempted to download an update to the engine ECU or has anyone done this (accidentally or otherwise)?

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Re: 508 CAN bus problem

Post by GiveMeABreak »

The reason I asked the question above is that there is a known issue with this engine on the 508 that can cause the following fault codes: U1108, U1118, U1218, U1308 & U1318 when they appear together.

The bulletin concerns: Erroneous faults of the engine management ECU.

The technical service bulletin is: B1KW0112Q0. This concerns the 508 with the DW10CTED engine.

These 5 fault codes can occur when the engine ECU software has been updated or attempted to be updated.

No parts are faulty but you may need to take it to a dealer to rectify as the cure is to connect to PSA servers in internet connected mode with a technician log in:

"MANDATORY: Diagnostics must be performed with a diagnostic tool in an internet connected mode with mandatory technician identification: Select the "Guided Fault Finding" menu. Perform "read fault codes". At the end of the general test, wait for the launch of the Diagnostics tab (main screen with a choice of methods by domain). Exit the Diagnostics session by going back to the main tab. Confirm the message "Do you want to quit the current session?""


You do have a few others like U0122 - but this is an intersystems CAN fault - loss of communication (I won't go into the details) - but the only suspect is the engine ECU and as these systems are inter-related - if you are having multiple engine ECU faults, then this will also impact on the other systems as described. So my advice is cure the erroneous faults described in the TSB above and hopefully these other faults will clear too.

ketyow
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Re: 508 CAN bus problem

Post by ketyow »

Not in the last 1.5 year while I'm owner of the car. Neither in the past I think (I have all service documentation) - but I can't be 100% sure.

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GiveMeABreak
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Re: 508 CAN bus problem

Post by GiveMeABreak »

Ok, so you have the reason now - it is not unknown for a diagnostic code reader to cause problems when reading / changing the ECU parameters. It has also happened on the 407 and C5 X7 with the parking assistance - if the ECU is read with a clone device and any parameters are changed - it can cause the data not to be written back incorrectly, leaving the owner with no or the wrong type of parking assistance.

ketyow
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Re: 508 CAN bus problem

Post by ketyow »

So, as it wasn't updated it might be the defective ECU itself? Especially when CAN voltages are too high (I guess that even in case of update failure voltages on CAN would not change). I didn't use Diagbox for more than year (FAP applicaton is enough if nothing happens - this one I used a lot, only for read; OBD interface is Vgate Icar Pro) so there is no chance of accidental update.

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Re: 508 CAN bus problem

Post by GiveMeABreak »

The issue would indicate the engine ECU is not faulty - but can produce these faults randomly. So don't get too hung up on CAN voltages at this stage because when some of these faults are present they can cause the engine ECU to deactivate certain functions and that in itself can cause other fault messages that are not really faults.

Deal with the engine ECU issue first as mentioned in the bulletin and then when these have finally cleared, you can deal with any others that remain (if any).

I wouldn't want to speculate on other issues that may not exist, when we know for sure there is a specific issue and TSB on this vehicle with this engine.

ketyow
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Re: 508 CAN bus problem

Post by ketyow »

Ok, thanks for help. Looks like I will need to take car to an authorized car service with internet connection for DiagBox. Hopefully they won't purge my wallet ;-)

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Re: 508 CAN bus problem

Post by GiveMeABreak »

To be honest I would demand they do it free of charge as it is a know fault! No harm in asking :-D