Garage Support

Back to Forum

Post a Response

Seat Leon II 1.9 BKC 2005 - CAN bus communication faults #

Posted by Lee Hemmings on March 16, 2012, 8:00 am

Year of Manufacture *: 55 plate
( Optional ) Engine Code or CC: 1.9 bkcengine

Hi chaps, i have had this Seat now since monday, every module as a can bus communication fault relating to other different modules around the car, but the main one is 'powertrain' which pops up in alot of them, (engine ecu)
Out comes the scope, i scope the 16 pin first-6&14 just to check the intergater of the system and the canbus is poor. Beccause i have alot of powertrain faults i go to pcm, and again same, i check with koeo with the pcm disconnected and still the same, same with abs.Go to the cluster and the same,but i disconnect the cluster and it canbus comes back for a short period of time and i am allowed to clear every fault code which would not happen before, anyway when i scope again the can bus is poor but not one fault code as reappeared, i did scope the can bus module aswell. I have drove car about 20 miles and no faults but can bus is poor when scoped- confused.
I have vagcom, is there a way of useing vagcom to tell if the gateway can talk to other modules etc or use the tool better to assist me ?
and any thoughts appreaciated ?

Re: Seat leon mk2, can bus communication faults

Posted by keith brown <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT1429' width='330' height='300' border=0 style='border:none;'> on March 16, 2012, 11:48 am, in reply to "Seat leon mk2, can bus communication faults"
Keith Brown

"canbus is poor"
Any results you can post?
whats the actual prob with car,inc fault codes
im sure vag has a cateway check box! im going to boot it up and see ,keith

Re: Seat leon mk2, can bus communication faults

Posted by Lee Hemmings on March 16, 2012, 12:47 pm, in reply to "Re: Seat leon mk2, can bus communication faults"
Message modified by board administrator March 16, 2012, 3:14 pm

yes how do i get my scope up that i hsve saved in my library ?
faults were just every single light on the dash, and then when car wouldet start the customer finally decided its time for garage.
Car now starts with no fault codes in any modules since cluster disconnection, but can bus still bad on the scope which i am intested in.
thanks

Re: Seat leon mk2, can bus communication faults

Posted by Darren Bamford <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5465' width='330' height='300' border=0 style='border:none;'> on March 16, 2012, 6:21 pm, in reply to "Re: Seat leon mk2, can bus communication faults"

Hi Lee

Have you got the schematic of this vehicle with reference to its CAN-bus structure and layout?

Are you aware of the Gateway module / diagnostic interface.?

Have you had any training or self study CBT on CAN-BUS?.

Don't assume The CAN-Bus layout is the same for all makes and models. They are not..

This is a classic example again of "if you do not understand what you are testing ,how can you test it"..

Re: Seat Leon II 1.9 BKC 2005 - CAN bus communication faults #

Posted by Matt Booth <iframe src='https://members4.boardhost.com/ukautotalk/info/user=ukat3028' width='330' height='300' border=0 style='border:none;'> on March 16, 2012, 8:10 pm, in reply to "Seat Leon II 1.9 BKC 2005 - CAN bus communication faults #"
Matthew Booth

Hi Lee,

Vag com can indeed help a bit. Go into the gateway (19?) and check measuring blocks 125 upwards. 125 to 127 are for the powertrain bus IIRC. It will list each control unit on the bus and have a 1 if it can communicate with the unit or a 0 if it cant.

The instrument cluster connects directly to the CAN gateway - it is seperate from any other bus. Interesting how it will start with the cluster disconnected though as it has the immob. built in.

Would be interested to see a complete vehicle scan, and some scope traces.

Matt

Re: Seat leon mk2, can bus communication faults

Posted by Lee Hemmings on March 17, 2012, 12:05 pm, in reply to "Re: Seat leon mk2, can bus communication faults"
Message modified by board administrator March 17, 2012, 12:31 pm

No Darren I dont have the layout to the can bus struture and yes I do understand can bus. Have you not read my first post as if you did you would see that I am fairly compentant with electronics but dont claim to know everything. Therefore is this not a classic example, this is someone asking for advice, help etc which is what the forum is about!

Re: Seat Leon II 1.9 BKC 2005 - CAN bus communication faults #

Posted by Lee Hemmings on March 17, 2012, 12:09 pm, in reply to "Re: Seat Leon II 1.9 BKC 2005 - CAN bus communication faults #"
Message modified by board administrator March 17, 2012, 12:18 pm

Hi Matt, yes i have done the gateway controller, cheers bud, sorry what i should of said was when the engine was already running, i dis-connected the cluster as the engine is already de-immobilized, and then scoped the plug to see if the canbus came back.
I have a complete vehicle scan printed out, didet save it, i also save my scopes, but dont know how to upload.

Re: Seat leon mk2, can bus communication faults

Posted by Darren Bamford <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT5465' width='330' height='300' border=0 style='border:none;'> on March 17, 2012, 5:37 pm, in reply to "Re: Seat leon mk2, can bus communication faults"
Darren Bamford

Hi Lee

I can see you are asking for Advise, that’s why I asked the questions i did.
The response I get from these questions would give me a better understanding to the advice I would give.

This vehicle is fitted with a external gateway module. This is the HUB of the complete network and acts as the translator between all the various other "buses and networks.

Therefore when you stated you checked the pins 6 and 14 of the diagnostic socket the "can was poor". If you had the schematic of the CAN layout of this system you would see that is purely used as the diagnostic bus via CAN. (Used for communication purposes between the diagnostic tool and the vehicle systems).

This is why I said not all cars are the same with regards to CAN. If this was a 2005 Mondeo for example then checking the Pins 6 & 14 of the diagnostic would give you complete data transmission of the High Speed CAN network. This is because Ford Choose to Incorporate there Gateway internal within some other control unit and not a separate gateway module.

So putting your scope leads across these two pins and checking for a signal serves no purpose in diagnosing you problem ( on this Car )

From the gateway there are five “CAN networks” operating at different transmission speeds.

CAN-BUS Powertrain
CAN-BUS Comfort
CAN-BUS Infotainment
CAN-BUS Instrument panel
CAN-BUS Diagnostic

All these networks are completely individual to each the only common connection is the Gateway module.

The instrument Can-bus and diagnostic Can-bus are the Buses that have no other node connected to there bus.

All the other Can-bus networks can have several other nodes connected to there network.

The point I was making is there is lots of general information out there, which does explain the basic concepts of CAN-bus and some foundation. But this does not always relate to every vehicle.

Surely if you have a good understanding of electronics and CAN-bus then you should agree you should not really be attempting this type of repair without the correct schematics and product knowledge. From your post I can see you are half way there because you clearly have invested in the correct tools.

Like Matt as said you can check the various if the various networks and nodes are active by looking in dynamic data

MVB 125 to 127 will show all modules on the (powertrain bus)

MVB 130 to 133 will show all modules on the (comfort bus)

MVB 140 to 141 will show all modules on the (infotainment bus)

Make sure you have your sample rate and time base set to high and fast rate to capture the data.

Also Try the serial decoding function with Pico, but make so you have the Red lead connected to the CAN H signal and black to CAN L signal.

If time allows I could be doing some Training sessions towards the end of this year that will cover this in more detail.

Hope this helps

Darren………….

Re: Seat leon mk2, can bus communication faults

Posted by lee hemmings <iframe src='https://members4.boardhost.com/ukautotalk/info/user=ukat3416' width='330' height='300' border=0 style='border:none;'> on March 17, 2012, 7:18 pm, in reply to "Re: Seat leon mk2, can bus communication faults"

Hi Darren
your secound post is much more friendly and informative. Fact is my knowledge on can bus is higher than most out there, and that is purely because i believe in r&d and do so on a daily basis to constantly improve my knowledge on the complex of engine electronics, therefore i couldet dis-agree with you more about tacking this job- so if i do as you say i dont attempt it- and therefore learn zero, on the other hand i make use of my product knowledge and expand it, and repair it (maybe with help)i climb the ladder.
Ok i scope the 16 pin plainly and simpley as somewhere to start, always start with basiscs.
Darren you seem to have a far greater capacity than most- me included, so can you elobrate on the serial decoding function with scope please.
No matter what, i will see this right to the end so all information is much appreaicated.
Ps Do you have the schematics you could share ?
Yes i would be intrested in any course that could provide a useful tool in the furture.
thanks lee

Re: Seat Leon II 1.9 BKC 2005 - CAN bus communication faults #

Posted by lee hemmings <iframe src='https://members4.boardhost.com/ukautotalk/info/user=ukat3416' width='330' height='300' border=0 style='border:none;'> on March 18, 2012, 4:47 pm, in reply to "Seat Leon II 1.9 BKC 2005 - CAN bus communication faults #"

I think i may be narrowing this down after studing your post Darren.
All modules have 01312 fault code stored, relating to powertrain canbus.
They are all connected indirectly via can gateway, therefore the airbag module as that particular fault code stored, i ask myself how is it stored there,either the powertrain or steering is not communicating(as they are on the same bus), or the gateway is not passing the info onwards-or wiring between powertrain steering and gateway ?. I may be way out here, but for me it makes sense.

« Back to index

[ Garage Support ]

Copyright © uk autotalk