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Model specific boards => Golf mk3 => Topic started by: BenGTI16v on 26 May 2012, 15:33

Title: obd2 no communication to scanner
Post by: BenGTI16v on 26 May 2012, 15:33
Hi all, Im having  abit of trouble with my golf as the abs light has just come on  :sad: so I plugged it into a scanner and it came up with no communication. I did a bit a research and found out that if you have an aftermarket stereo fitted this can give you problems, so ive tried scanning it withoutit connected aswell with no luck. I have battery voltage to pin 16 on the obd2 port but I dont know what else to test.

Car is a 95 mk3 gti 16v and im using a snap on verus

Any help appreciated thanks.
Title: Re: obd2 no communication to scanner
Post by: ttelracs on 26 May 2012, 15:47
Same issue !
Handbrake light came on so popped up to see my cousin who has a hand held scanner and could get no reading at all. It stated it was unable to communicate or no link detected. I too have an aftermarket head unit fitter, a Kenwood of some sort which it came with and wonder if this is why no joy ?

No answer though !
Title: Re: obd2 no communication to scanner
Post by: BenGTI16v on 26 May 2012, 16:22
I have tested some of the pins on the port and I have battery voltage to pin 16 a good earth at pin 7 I believe pin 4 in the k-wire which should give a voltage but only gives 0.01v
Title: Re: obd2 no communication to scanner
Post by: BenGTI16v on 26 May 2012, 16:40
Same issue !
Handbrake light came on so popped up to see my cousin who has a hand held scanner and could get no reading at all. It stated it was unable to communicate or no link detected. I too have an aftermarket head unit fitter, a Kenwood of some sort which it came with and wonder if this is why no joy ?

No answer though !
Checked you brake fluid level? sometimes the little plunger thing for the senser sinks in the resovoir causing the light to come on.
Title: Re: obd2 no communication to scanner
Post by: itavaltalainen on 26 May 2012, 17:32
What OBD scanner are you using? Which cable? VWs of the mid to late 90s have OBD2 sockets but are not OBD2 compliant, hence you need a VW specific tool. Other than that might be a wiring issue....
Title: Re: obd2 no communication to scanner
Post by: BenGTI16v on 26 May 2012, 17:49
What OBD scanner are you using? Which cable? VWs of the mid to late 90s have OBD2 sockets but are not OBD2 compliant, hence you need a VW specific tool. Other than that might be a wiring issue....

Ive used a snap on verus and a snap on ethos both didnt work but they could connect to another mk3 golf I had in at work but that was a 1.4 97 plate.
Title: Re: obd2 no communication to scanner
Post by: Ess_Three on 26 May 2012, 18:46
As far as I know, no Mk3 was ever fitted with a diagnostic line to the Stereo...it's just too early.
So changing the Head Unit won't cause you any problems.
Title: Re: obd2 no communication to scanner
Post by: itavaltalainen on 26 May 2012, 19:51
It's not about a diagnostic line to radio. It's the speed signal for the gala function, if connected to some radios this can for whatever reason mess up comms with diagnostics. I suppose it can confuse the ECU.
Title: Re: obd2 no communication to scanner
Post by: Ess_Three on 26 May 2012, 20:01
It's not about a diagnostic line to radio. It's the speed signal for the gala function, if connected to some radios this can for whatever reason mess up comms with diagnostics. I suppose it can confuse the ECU.

Is there a speed signal in the radio wiring harness on the Mk3?
There ism't on mine.

I thought Gala came later on, with the Mk4?
Title: Re: obd2 no communication to scanner
Post by: itavaltalainen on 26 May 2012, 20:58
All mk3s should have gala signal. Pin 1 on ISO connector should be that ;)
Title: Re: obd2 no communication to scanner
Post by: BenGTI16v on 26 May 2012, 21:24
All mk3s should have gala signal. Pin 1 on ISO connector should be that ;)
should i disconnect it if i have an aftermarket stereo?
Title: Re: obd2 no communication to scanner
Post by: Ess_Three on 26 May 2012, 21:35
All mk3s should have gala signal. Pin 1 on ISO connector should be that ;)

There are two connectors, a brown 8 pin (speakers) and a black 8 pin (power, ground, lights dim, to antenna etc)
Where is the Gala signal?

UK Mk3s never had Gala equipped stereos...and I'm certain mine has no unused wires in the black plug.
Title: Re: obd2 no communication to scanner
Post by: itavaltalainen on 26 May 2012, 22:04
Just had a look at my 96 UK Golf, wt-bl wire on pin 1, but my  Euro LHD one had that as well. It's unused on my aftermarket Sony (adapter from ISO to head unit has no wire going to pin  1).
So you might not need to disconnect it. I'll look up wiring for diagnostics, my AAM does also not connect and the K409 adapter and VAG COM worked fine on my 2E.
Title: Re: obd2 no communication to scanner
Post by: BenGTI16v on 26 May 2012, 22:48
Just had a look at my 96 UK Golf, wt-bl wire on pin 1, but my  Euro LHD one had that as well. It's unused on my aftermarket Sony (adapter from ISO to head unit has no wire going to pin  1).
So you might not need to disconnect it. I'll look up wiring for diagnostics, my AAM does also not connect and the K409 adapter and VAG COM worked fine on my 2E.

Appreciate all the help guys, As far as I can see without pulling the dash off theres no breaks in any wires anywhere, plugged in the oe stereo and still had no change in k-wire voltage. Does anyone know if I fix my abs problem e.g I find a wheel speed senser down will the llight go off or will I have to clear the codes?
Title: Re: obd2 no communication to scanner
Post by: BenGTI16v on 26 May 2012, 23:07
Just had a look at my 96 UK Golf, wt-bl wire on pin 1, but my  Euro LHD one had that as well. It's unused on my aftermarket Sony (adapter from ISO to head unit has no wire going to pin  1).
So you might not need to disconnect it. I'll look up wiring for diagnostics, my AAM does also not connect and the K409 adapter and VAG COM worked fine on my 2E.

Appreciate all the help guys, As far as I can see without pulling the dash off theres no breaks in any wires anywhere, plugged in the oe stereo and still had no change in k-wire voltage. Does anyone know if I fix my abs problem e.g I find a wheel speed senser down will the llight go off or will I have to clear the codes?
Also I have noticed there is only 4 pins on my obd port 4,7,15 and 16 I would have thought there were more.
Title: Re: obd2 no communication to scanner
Post by: Ess_Three on 26 May 2012, 23:16
Does anyone know if I fix my abs problem e.g I find a wheel speed senser down will the llight go off or will I have to clear the codes?

I think the ABS light will go out after a few minutes of driving, but the fault will remain stored until cleared properly.


Quote
Also I have noticed there is only 4 pins on my obd port 4,7,15 and 16 I would have thought there were more.

I'm sure that's correct.
Early Mk3s had the 2 x 2 diagnostic connectors, so only 4 wires make sense.
Diagnostics on Mk3s are fairly basic anyway.
Title: Re: obd2 no communication to scanner
Post by: Bandit127 on 27 May 2012, 07:23

Also I have noticed there is only 4 pins on my obd port 4,7,15 and 16 I would have thought there were more.
Is it possible you have have OBD 1.5? That would need an OBD 1.5 compatible scanner to work.
http://www.autos.com/aftermarket-parts/your-guide-to-chip-tuning-a-vw (http://www.autos.com/aftermarket-parts/your-guide-to-chip-tuning-a-vw)
Quote
Some 1994 and 1995 model year cars are equipped with an OBD-1.5 system which utilizes a 16-pin connector, but uses the OBD-I system.

Re pin 15 having 0.1V... This diagram shows the cable connector for OBD2. Pin 15 carries the RTS signal - so it is an input and gets its power from the reader. Pin 7 carries the data and will have about 6V if you set your meter to AC and the line is transmitting.
http://pinoutsguide.com/CarElectronics/obd2_simple_cable_pinout.shtml (http://pinoutsguide.com/CarElectronics/obd2_simple_cable_pinout.shtml)
Title: Re: obd2 no communication to scanner
Post by: Ess_Three on 27 May 2012, 10:10

Also I have noticed there is only 4 pins on my obd port 4,7,15 and 16 I would have thought there were more.
Is it possible you have have OBD 1.5? That would need an OBD 1.5 compatible scanner to work.
http://www.autos.com/aftermarket-parts/your-guide-to-chip-tuning-a-vw (http://www.autos.com/aftermarket-parts/your-guide-to-chip-tuning-a-vw)
Quote
Some 1994 and 1995 model year cars are equipped with an OBD-1.5 system which utilizes a 16-pin connector, but uses the OBD-I system.

Re pin 15 having 0.1V... This diagram shows the cable connector for OBD2. Pin 15 carries the RTS signal - so it is an input and gets its power from the reader. Pin 7 carries the data and will have about 6V if you set your meter to AC and the line is transmitting.
http://pinoutsguide.com/CarElectronics/obd2_simple_cable_pinout.shtml (http://pinoutsguide.com/CarElectronics/obd2_simple_cable_pinout.shtml)


I suggest you ask about for someone local with VCDS (VAG Com) because if the car has either the 2x2 connector, or the full OBD plug, VCDS will talk to it.
I've never found a diagnostic equipped VW yet that I've not been able to interrogate using VCDS.
Title: Re: obd2 no communication to scanner
Post by: BenGTI16v on 27 May 2012, 12:32
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?? :huh:. 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.
Title: Re: obd2 no communication to scanner
Post by: itavaltalainen on 27 May 2012, 12:49
you only need 4 wires, just opened up my adapter :)
Title: Re: obd2 no communication to scanner
Post by: Ess_Three on 27 May 2012, 13:16
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.
Title: Re: obd2 no communication to scanner
Post by: Ess_Three on 27 May 2012, 13:17
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?? :huh:. 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.
Title: Re: obd2 no communication to scanner
Post by: BenGTI16v on 27 May 2012, 14:21
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.
Title: Re: obd2 no communication to scanner
Post by: BenGTI16v on 27 May 2012, 14:28
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

Title: Re: obd2 no communication to scanner
Post by: Bandit127 on 27 May 2012, 15:22
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). 

Title: Re: obd2 no communication to scanner
Post by: BenGTI16v on 27 May 2012, 16:28
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
Title: Re: obd2 no communication to scanner
Post by: Bandit127 on 27 May 2012, 17:21
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.
Title: Re: obd2 no communication to scanner
Post by: BenGTI16v on 27 May 2012, 17:55
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!
Title: Re: obd2 no communication to scanner
Post by: BenGTI16v on 28 May 2012, 18:29
ok so it still doesn't work so ill have to try and find a place with vag comm  :sad:
Title: Re: obd2 no communication to scanner
Post by: Ess_Three on 28 May 2012, 19:33
ok so it still doesn't work so ill have to try and find a place with vag comm  :sad:

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?
Title: Re: obd2 no communication to scanner
Post by: BenGTI16v on 15 July 2012, 21:01
Hi guys bit of an update sorry for the long delay, Im still suffering with this problem had it read with vcds still no communication so im coming to the conclusion that its a wiring fault somewhere. The car makes a wierd clicking/buzzing sound three times when trying to connect which the guy said hed never heard one do before and seems to think this is probably the cause of the fault any ideas what it might be?

Thanks!! :smiley:
Title: Re: obd2 no communication to scanner
Post by: lars2.0 on 15 July 2012, 22:00
I have the same problem...And it's for the "OBD Wire" because only read cars from 1996...