scMaverick

Hello,
here is the situ, my ecu scanner is not working, apparently it doesnt have a signal.
There's supposed to be a bridge line in the stereo that would enable the scanner port when the radio is turned on.
I dont have the original audi stereo anymore but an aftermarket stereo, Im guessing that bridge line was cut and forgotten making the scanner not to work anymore.
This is supposed to be the connection diagram of the original stereo>




Audi A4 97 B5 stereo diagram

But no idea which is the line for the ecu scanner??

Or would you happen to have another idea for me to check why the scanner is not receiving a signal?
Thanks very much.

AudiMick

Not sure what you are trying to achieve here!

You may be looking for something that isn't there, the signal wire is called K-line. Your car has a K-line but:

In the US 95-97 had an Audi Delta (made by Blaupunkt) stereo head unit and it didn't have a K line connection (no wiring) , when they changed to Concert I (made by Panasonic )head unit in mid year 98 they added the K-line. The pic you have is for the Concert I head unit not the Delta.

An aftermarket head unit can't use the K-line.

If the K line is not working, since there is no K line wiring to the head unit in your 97 , the usual culprits are ABS module, cluster, climate control and comfort. Unplug them one at a time until you can connect.

Pic shows the wiring for Delta and Concert note Pin 3 is 12 volt on the Delta, K line on the Concert. that's the only difference except for the extra plug IV for Nav and phone on the Concert.

Also note, removing a connection to one module doesn't cause K line to be in-operative. Unlike CANBUS as used in the later Audi cars, K lines are wired in parallel so if you unplug the bad unit the other modules will run.

See this link below from Ross-tech. This is probably NOT your problem as you have an early car, but there is interesting info here about aftermarket radio problems in a newer Audi.

Reading between the lines you can see why the problem can occur. Also pinout for OBDII plug.

Ross-Tech: VCDS: Afterrmarket Radio Problem

*********************

On my 96 A4 I added the K-line to the wiring loom (spliced into K-line at the climate control plug) and installed a Concert I so I could use an iPod/ iPhone adapter Lot's of folks have done this. Worked great and retained the Audi OEM look.

scMaverick

Hello Mick,
thanks much for your response, very useful info you've provided.
I didnt know the external modules could interfere with the scanner, which is weird anyway as the scanner is supposed to tell you something is bad and not the other way around :P
Anyway, I forgot to mention my Audi is european version and not from the US, would it still be the same with the concert 1 vs the Delta?
Also, the only light that turns on during ignition is the airbag light, but that always goes off after some seconds, perhaps a couple of minutes. That is the main reason why I wanted to scan the vehicle. But the ABS light has never indicated any faults with that module. Or this shouldnt matter anyway?
One more detail, always when I turn the ignition the odometer (red LCD screen) will display "Line 2", then again after a couple of minutes it goes back to displaying the actual kms. From googling it seems like that means I should take the car to the dealer for routine inspection so I never thought it could be a problem.
But so, I will try disconnecting the ABS module and trying to scan, I think this is just lift up the hood and disconnect the electric connection from the ABS.
Then I will try climate control unit, which I guess is the one in the lower dashboard, by removing the stereo, the screws, the covers and then unpluging it.
Finally will try the cluster, this one is easy to remove but hard to fit in again as its shape is not very comfortable to slide in, thats why I want to leave it last.
It should be one of those interfering right.
Thanks again!

AudiMick

Comfort alarm module is in the trunk (boot) that is another common failure. They get wet.

Since all the modules are connected in parallel it's just a matter of finding the offending one which can pull the entire K-line down. Also check your 12 volt at pin 16 of the OBDII plug.

This is all the different radios, not sure what your A4 would have.

Ti Kan: Audi Radios

scMaverick

Right on the money! So instead of disconnecting the modules I simply removed their corresponding fuse from the fuse box one by one.
It seemed like the climate control unit was the one causing the problem because the scanner started to work after I removed that one.
Only problem is that I was testing with VCDS lite still in shareware mode and it doesnt decode more than 1 code nor let me perform other tasks like TPS alignment.
Does what happens when you buy the cheap vag com cable from ebay. Their freaking cracked vag com 409.1 never recognized the interface... anyway will have to figure this one out later,
Thanks again!