Blink codes and Vagcom

[urq20v]

Hi from NZ,
I have a 1994 ABY S2 which will not communicate with Vagcom or show blink codes.The car seems to run fine,but I would like to be able to monitor engine parameters etc.I have tried the Vagcom on other S2s,both 3B and ABY with no problems.
When connected to Vagcom I get a "too many communication errors to continue" message.Nothing happens when I try to read blink codes.I have replaced the ECU but it makes no difference.
Any Ideas on what might be the problem would be greatfully received.

Rex

[S2central.net]

Check the integrity of OBD wiring in fusebox (blue, black and white connectors).
Also check fuse 31 (from memory) for the OBD comms.

You should have 12V across the black connector permanently.

If you have a multimeter you should be able to check the wring from the blue connector and white (K/L pins) into the ECU - any break or short there will give problems.

I can talk you thru the schematics on this if need be, but S2 Central includes a pinout for this stuff.

Good luck - sounds like a silly one... bad earth maybe ?


Paul

[urq20v]

Thanks for the info Paul.I have checked all wiring for continuity and shorts from the diagnostic connectors back to the ECU with no problems found.I also checked all earth points from the ECU to their various termination points.All earthpoints are solid.Is there an earth required for the ECU case?My ECU just sits up behind the glovebox without a mounting bracket,which I guess was originally earthed.

[S2central.net]

If the ECU is missing a bracket then somebody has been at the thing. I suspect that maybe non-standard chips have been fitted such that OBD comms are broken - this is sadly the norm on many 'eBay' chips. If you can open the ECU, let me know what chips, numbers and printed codes you can see and I'll tell you if they are stock or not.

ABY ECUs are NOT socketed in the factory. Stock chip numbers for a non-immo ABY end in 021 and 022 which should be visible on silver chip stickers.

Paul

[urq20v]

The ECU has been socketed,but has the standard 021 and 022 chips installed.As I mentioned earlier,another ECU was substituted for the original,but made no difference to being able to read blink codes or interface with Vagcom.I have been trying to
find the reason for this problem for some time now,but have made no headway.Everything seems to be OK with respect to the wiring etc,but obviously something is not right.I think I will take the car to my local Audi dealer and see if their VAG analyser will communicate with it.