A8 Tech Please Help

[chris96a4]

I have a 2005 audi A4 2.0tdi with a christmas tree for a dashboard the car has had some body work carried out with quite extensive loom and component removal and refit.
Warning lights present.......abs, brake warning, esp, (all linked as i understand) also Airbag, and seatbelt warning.
So far I have checked all abs sensors with an occiliscope, all function correctly, I have replaced the brake switch, (both centre and side brake lights functioning correctly, although they come on very slightly out of syncronisation, only very slightly) checked and replaced both brake light bulbs.
I have also had two different people try to read fault codes, one had a 'launch' fault code reader, the other was a vwtool laptop based system neither kit will access the engine, airbag, brake, steering system or instrument panel although they did access stereo, air con etc fine.

I have trawled the site and see that you are fairly local, can you please help


Any advice from anyone would be gratefully received

Cheers

Chris

[elPaulio]

Hey there Chris,

Sounds like you've got a handfull there!!

My advise, firstly tackle things one at a time.
Secondly, (slightly contradicting for the above!!) Yes, the ABS, Brake Warning and ESP are likely to be linked!
I assume that the battery has been disconnected during this loom removal/replacement. Have any of the modules been changed out? In particular the Steering Control System Module behind the steering wheel? I know from a Cruise Control retro-fit that replacing this gives up these errors as the steering angle sensor needs to be calibrated afterwards and this is used by all three circuits!! Might be worth a try! If you go to the Ross-Tech Wiki pages you can find the procedure there!
As for the brake lights being slightly out of sync that is normal as the switch at the pedal is actually two switches, one for the centre LED lights and the other for the two outer lights.

I would definately recommend getting someone with VCDS (Vag-Com) to plug in to your motor and see what faults are showing up!

Hope that helped slightly??

Paul

[a8 tech]

I have a 2005 audi A4 2.0tdi with a christmas tree for a dashboard the car has had some body work carried out with quite extensive loom and component removal and refit.
Warning lights present.......abs, brake warning, esp, (all linked as i understand) also Airbag, and seatbelt warning.
So far I have checked all abs sensors with an occiliscope, all function correctly, I have replaced the brake switch, (both centre and side brake lights functioning correctly, although they come on very slightly out of syncronisation, only very slightly) checked and replaced both brake light bulbs.
I have also had two different people try to read fault codes, one had a 'launch' fault code reader, the other was a vwtool laptop based system neither kit will access the engine, airbag, brake, steering system or instrument panel although they did access stereo, air con etc fine.

I have trawled the site and see that you are fairly local, can you please help
I am available on 07814 019599

Any advice from anyone would be gratefully received

Cheers

Chris

Ok you have a drive train bus issue.
You need to check if you have drive train can communication.
I would connect your vag software reader and disconnect the 4 control units one by one whilst checking to see ifyou can access gateway in the dash.

you see if one or more control units are corrupting the drive train then the communication network will fail a4 uses k wire and can network hence you can access some other sytems.
Also there maybe a bad earth here

You can check all the can signals in 08 air con measured value blocks 126 126.
This will save you time and confirm if the network has a fault like i suspect.

[a8 tech]

Also as gateway is part of the dash the fault may lie there as ive seen this kind of fault from jumpstarted engines frying the dash.
Gateway is the processor that takes all the network information speeds input values and processes the binary info to the other networks so when you turn the ignition key the gateway sees the start command from the key end enables the engine control unit to allow the engine to start in basic terms

[chris96a4]

Thanks for the assistance but as yet no go

I disconnected the airbag module, abs, and dash one by one but no change, each time trying to access the other 3 modules using vag-com, I also tried access with vwtool but the same result, 'no responce from controller'
my vag-com is unregistrered so unable to carry out the "08 air con measured value blocks 126 126" test.

I don't know if it helps but cruise control works fine.....

Is it worth carrying out a contiuity test along the diagnostic wire that daisy chains these modules? if so which colour is it?

Any other suggestions?

Cheers

Chris

[a8 tech]

Chris i would try to use a tested version of vag com 704 or vcds 805 and post the diagnostic log.
I no you are frustrated but until you get some fault codes to me its anybodys guess what the fault is and it might just be the software you are using cant read the car for what ever reason.
You could scope the drivetrain bus signal but i think you need full version vag com to progress.

[chris96a4]

Sounds good I will post to see if anyone in the area has access

[chris96a4]

Do you know which wire daisy chains from the diagnistic socket to all the modules, would be good for peace of mind to check continuity.

Cheers

Chris

[chris96a4]

Many Thanks for your help guys,

Managed to find a helpful chap on the forum locally (dozz) who had the later software, he was able to get into all systms, clear codes (many many codes) and now all is sorted.

Happy days

[a8 tech]

well done