obd2 no communication to scanner

[Ess_Three]

you only need 4 wires, just opened up my adapter

As I said previously, the early cars had 2x2 connectors...so the Mk3 only needs 4 wires.

[Ess_Three]

thanks for the replies everyone. As far as I can see Comparing my car to the diagram im missing pin 5 which I guess would be the signal ground? I have pin 4 which is the chassis ground or the other way around?? . I also have the unswitched live feed. Didnt know what pin 15 did till now, I will probably will head off to my local dealer or specialist to see if they can read it.

Where abouts are you?

Isn't there anyone with VCDS who can scan it locally for you?
There are plenty of users on here with it who may be able to help out.

[BenGTI16v]

warwickshire, I went out and tested my pin 15 and im getting 10v dc on it which is the grey/white wire I beleive is the k-line? I jiggled the connecter on the back of pin 15 and managed to get it to show a voltage on the front of the port if that makes sense.

[BenGTI16v]

Sorry guys ive completly messed it up when explaining... as it stands:

Pin 4 I have a good earth
pin 7 k-line grey/white wire? 10v dc
pin 15 no volts ac or dc
pin 16 battery voltage

[Bandit127]

Sorry guys ive completly messed it up when explaining... as it stands:

Pin 4 I have a good earth
pin 7 k-line grey/white wire? 10v dc
pin 15 no volts ac or dc
pin 16 battery voltage

Sounds good to me. If you look at the wiring diagram of the connector in my earlier post, signal and chassis ground are bridged together (pins 4 and 5). 

[BenGTI16v]

Thanks for the help I will try to connect it again at work tommorow, I though you said I should have 6 volts ac on pin 15? I dont have any reading

[Bandit127]

Should have been clearer...

Pin 15 is the RTS so it sits waiting for the scanner/laptop to send it a signal. With nothing plugged in - 0V then so that is correct.

Pin 7 is the data one. My guess was 6V AC based on a square wave - 10V should be fine.

I think you have the right amount of volts in the right places.

However, I also think you might have OBD1.5 which means an ordinary OBD2 scanner won't work. According to that link the data will be sent in OBD1 format (if you actually do have OBD1.5).

As Ess_Three said, VAG COM is probably the answer if that is what is going on. 

Good luck tomorrow and keep us posted.

[BenGTI16v]

obd 1.5 would make sense as the car is a late 1995 on an n plate, I cant see any problems if it was obd2 as to why it would not work. Anyway will try it again tommorow if it doesn't work then off to the specialists and thanks alot for the help!

[BenGTI16v]

ok so it still doesn't work so ill have to try and find a place with vag comm 

[Ess_Three]

ok so it still doesn't work so ill have to try and find a place with vag comm 

Have you asked on the Forum?
I'm sure there will be a member near you that would scan it for you...or at least try.

Why not post a request in the Mk3 section to start with?