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zenza

Diagnosis plug (OBD plug)

Question

Could someone please point me where goes the White-Blue wire ,one of those three found in Diagnose Data Link Plug (OBD plug) ? It's a Polo 6n 1,4 AEX MPI, 44 kw.

There are three wires, two are + and - 12V and the third is the one with data from ECU.

I've tried several different VAG interfaces and no chance to coonect to ECU, everytime " No response from controller" wich leads me to think the data wire is broken somewhere.Thank you !

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27 answers to this question

Pin 7 (grey/white) of the obd connector goes to a junction box above the relay box, there is a two pin connector onto this junction box

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Many huge thanks, will you please tell me further more, what's after that 2 pin junction box? I'd like to follow it to it's end, the ECU I soppose. Perhaps, is the same White-Gray wire leading to ECU?

Edited by zenza

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Ok, from pin 7 of the obd it goes to pin 2 of the two pin connector on the junction box, then comes out of the junction box on a four pin connector pin X, it then goes to pin 6 of the immobilliser box, it comes out of the immob on pin 2 (white/Yellow) goes back into the relay box on connector U pin 2, out of the relay box on connector G2 pin 2 (grey/white) to pin 29 of the ecu

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That's invaluable . Thank you !

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That's invaluable . Thank you !

I forgot to add that the information is correct for upto late 97 models

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Fits to me, mine is '96. I'll go tracking the wire, it's awfully bad being unable to diagnose the car.

Edited by zenza

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I have had problems connecting to my car, It will only connect to my old slow processor (300Mhz) laptop, it does'nt want to know when I use my 2Ghz one, but I also have a Haynes profesional hand held unit with a VAG pod and I tend to use this to just read the codes

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If I take a straight wire between pin 29 on ECU and OBD-Data Link Connector, Will I solve somthing or I could damage something?

I just don't understand why this has to pass trough the Immobilizer module..

Edited by zenza

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If I take a straight wire between pin 29 on ECU and OBD-Data Link Connector, Will I solve somthing or I could damage something?

I just don't understand why this has to pass trough the Immobilizer module..

If the car is starting OK then the wire from pin 2 of the immob to pin 29 on the ecu must be OK as it uses this wire for the immob signal for a good key info and so enabling the ecu to allow the engine to run

Nigel

07765060766

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Spot-on, it works like a dream, it was the little junction box a bit corroded. I dare now to bother with another old problem I have for over two moths, an speedometer issue.

It barely works and not at all recently, I changed the speed sensor, cleaned all the connectors,cheked and triple checked the earthing,the barrel connector..

No need to say when the speedo is dead,the petrol gauge moves as the gas walks through the tank.. They work together somehow.

The VSS(vehicle speed sensor) has three wires, two are + and - 12V(and they're ok), the middle one is the "signal wire". I tracked it, and as Hayness wiring diagram shows as well, it goes to pin 27 on Instrument Cluster .

Well, when the speedo works out ok, there is a small ~4V on this wire and 0 volts when the car is stopped but engine(key) on,good now.

But when the speedo is dead, I always find 10V on this wire, all the time, regardless the car is either moving or not (the key on though) .

I can't imagine what could cause to appear this high 10V voltage on this wire, but I think this why the speedo stops to work. Will you please help me somehow with this,I'll get mad very soon.I can't call you, I'm having serious hearing loss. Thanks again !

Edited by zenza

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One problem down onto the next!

Pin 2 of the speedo sender is the signal (White/Blue) it goes to pin 7 of the 28 pin engine disconnect, from there it goes to connector G1 pin 11 of the relay box, comes out on connector U1 pin 11 (White wire) to pin 27 on the speedo unit, a possible cause for your odd voltage is pin 12 of connector U1 is the signal from the petrol level sensor, so you might have some intermittant tracking between these adjacent pins, or it could be the speedo unit has an internal fault?

The speedo signal also comes out of the speedo unit on pin 7 (purple wire) to connector U1 pin 1 on the relay box and out of the relaybox on connector G2 pin 1 (blue/white wire) to pin 36 of the ecu

Connector U1 numbers 1~13 on the left and 2~14 onthe right as seen on the picture

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This diagram and your explanations confirm my findings regarding the wire trackig, look what I did yesterday just to exclude the possibility of "touching" between wires inside the fuse box ; I've bypassed the fuse box by cutting the White-Blue wire coming from VSS just above the connector G1-pin 11, and did the same with the White wire that leaves the conn U1 ,pin 11 and tied them toghether,straight !

God, the speedo worked out instantly (I had the car rised on jack,geard in 1-st,engine on-LH wheel rolling),I rode arround the city for over an hour to make sure it's been solved for good. and I've heard the violins of happines... until this morning when the speedo died while working fine ,on my way to job. Can you picture how desperated I was, nothing else worked since,the 10V was present on the white-27pin Instrument Cluster.After this I wrote you my previous post.

I now believe it's the instrument cluster faulty, I had it on my table all the day,trying in vain to see something "wrong" on it's electronics.

I wonder if I've covered all the possibilities to diagnose this fault before starting to find another instrument cluster.

I would try to check something on Purple wire between Instrument Cluster an ECU.

Many,many thanks again for time and all.

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If there was a problem between the speedo and the engine ecu, it should of put up a fault code, now you can interrogate the system, so that would also rule out any wiring faults between the speed sensor and the speedo unit, only leaving an internal problem within the speedo units electronics drive to the stepper motor for the speedo needle

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I've ended buying a whole instrument cluster from an Ibiza (!) wich suprinsingly fits in and works out ok albeit having some more warning lights than mine, like side lights indicator or empty tank,safe belts wich, surprinsingly really work out , they're being disabled or missing on my old dash instruments.

Nigel thanks alot ,cheers!

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Good news you've fixed the problem, the Seat and Golf speedo units of the same age are direct replacements, but as you've found they also include some extra warning lights etc.

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I need a little help,

Just got a obd2 bluetooth elm327, when i plug it to my 6n1 it gets power and i can pair with it via Bluetooth but cant connect to ECU.

Tested it with a pegeut 206 sw (year 200X, like this one: http://quatrorodas.abril.com.br/imagem/580...eot206_abre.jpg ) and it works ok.

Tried diferent softwares but cant get any info from my 6n1 1.0 97.

Any solution?

Thanks in advance

----- edit -------

After removed some plastic to acces the port from behind i found that there are only 3 wires connected to OBD port:

RED -> PIN 16

BROWN -> PIN 4

WHITE/GREY -> PIN 7

http://imageshack.us/photo/my-images/9/img20111228222123.jpg

Edited by UrbanRider

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Can you acces the ECU trough a classic VCDS or other diagnosis tool ?

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classic = lite?

(sorry noobie here)

I used VCDS Release 11.11, tried other programs but no success

Edited by UrbanRider

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Check for +12v at the red wire (with ignition on) and the brown wire should be grounded.

HTH

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Mesured it right now and i have + 12v on the red wire with the brown grounded.

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Does the light on the adaptor come on when it's plugged in?

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yes, and i can connect to it (its bluetooth), but then the device cannot connect to car's ECU

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I would trace the white/grey wire, like the OP did, maybe you will find a similar fault as he did

To trace the wire follow what Nigel wrote

Ok, from pin 7 of the obd it goes to pin 2 of the two pin connector on the junction box, then comes out of the junction box on a four pin connector pin X, it then goes to pin 6 of the immobilliser box, it comes out of the immob on pin 2 (white/Yellow) goes back into the relay box on connector U pin 2, out of the relay box on connector G2 pin 2 (grey/white) to pin 29 of the ecu

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The ELM327 will not communicate with the car it is only for EOBD2 status cars which means any UK/EEC car registered after 2001 for petrol and 2005 for oil burners, some manufacturers implimented a form of EOBD2 prior to the deadlines, most of the blue ovals were compliant by 1996 as this was the date for compliance in the USA, but for some reason VW did'nt!!

You will need just the basic lead from ebay and a copy of VAGCOM/VCDS

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Thanks dixy

And thanks nige8021

I really tougth that my kar was obd2 :( i was already testing the k-wire from the connector looking for a short.

In that case what kind of lead should i be looking for? can you point me to the right direction?

Thanks again to both of you and sorry for my silly questions

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