HELP diagnostic Port not working !!

[aaron001au]

hey all , i have a 2001 mk4 golf with the 1.6L (AKL) engine in it.

the other day my air bag light came on when i was trying to fix my dash light , a fuse was pulled for the instrument panel while the key was on reds , i didn't think much of it and thought oh that's pretty easy to get rid of ill just pop in to my local vw dealer and get them to clear the code ... WRONG!

So they tried to clear the code but could not connect to the data port so i booked it in for them to fix it and clear the code.

i went down this morning and waited around for a few hours with no luck all, they said was the port is getting power but there is no communication to the gate way at all and i would need to book it in leave it there for a day so they can start tracing wires.

its booked in for next Thursday to get sorted ( i hope ) but its costing 140 a hour to do and then i have to pay parts on top if i need parts

so before i take it back is there any thing else i can try to get the port working or any reason it wouldn't be working?

they also said they think the J159 might be stuffed and need replacing


can any one help i dont really wanna be paying upwards of $1000 to clear a airbag light but i want the car fixed ......

[The One]

Do you have an aftermarket radio fitted?

[vdubmotorworx]

After market radios block CANBUS signals...remove the radio and try again! Dealer techs should know this...has happened since mk4 came out!

[The One]

Ross-Tech: VCDS: Afterrmarket Radio Problem

P.S: Why take a mk4 to the dealer? Plently of other places on the Gold Coast... Go see the boys at Eurotune in Miami, they will sort it out quick fast and cheaper than the dealer, do great work aswell.

[aaron001au]

was going to try the radio thing tomorrow , as i was doing some reading to night and just found this out , didnt even know about other places just thought vw would be best ill give euro tune a call tomorrow

[aaron001au]

i owe all you guys a beer , pulled out my head unit disconnected the harness and bam it all worked and cleared my codes !

[vdubmotorworx]

[aaron001au]

So im pretty sure this looped over wire is why the aftermarket headunit interferes with the diagnostic ports data flow .

So it i was to cut it off would my head unit still function fine and give me full access to the data port ?

Its kinda annoying knowing every time i need to scan my car the head unit has to come out ....

[The One]

All the info you need is in the thread I sent you mate. As it happens to be I'm a local on the GC and Brisbane, I like Corona's buddy .

Yeah speak to the boys @ Eurotune in Miami next time, they would have been able to tell you about the radio issue instead of trying to charge your hourly to 'fix'. Very knowledgeable workshop.

[aaron001au]

Oh didnt even see the link , my bad ... sonif i chop it all will be fine ?

Will deff go to eruo tune next time i need work done

[The One]

Check the wiring harness originally fitted to your vehicle (before your 'plug and play adapter') cut it and you should be fine.

[Snail Style]

LOL working at a VW dealer I saw a foreman struggle about 2 hours trying to figure this one out. Also saw a VW qualified 4th year apprentice waste a whole day on the phone to technical support trying to figure out battery drain in a MK5 with an RCD310 in it.

What you would assume dealer mechanics would know after years of experience is not always true, majority have no interest in the cars they work on and no interest to find out what causes a fault, only the fix for it.

[Sirocco20348]

Hmm I must have been lucky then. I just bought the harnesses from super cheap auto. I still have full communication.