i've failed my MOT on emissions and i can't get into the ECU via VCDS to check what i need to replace.

I fixed the wiring to the lambda sensor near the heat shield some time ago and think it may just need fettling, but i can't check the codes on the ECU nor the readings from the sensor to be sure my fettling has worked.

How can i get VCDS to work again? it just randomly stopped working and keeps saying "no response from controller" on every module. Plus it works fine on every other car i try so the cable and laptop and not the issue.

Any ideas?

Have you got an aftermarket radio fitted? as they can kill the diagnostics Also you might need a canbus lead as most of the gti controllers are canbus connected

Have you got an aftermarket radio fitted? as they can kill the diagnostics Also you might need a canbus lead as most of the gti controllers are canbus connected

i have got an aftermarket radio but its worked countless times before with it plugged in and i've tried unhooking it and it still won't talk. the lead i've got has worked with this car for 5+ years too, which makes me think the ECU is the problem.

The main gateway for the diagnostics is via the speedo unit, so that might be the problem if it's not communicating with any of the controllers

The main gateway for the diagnostics is via the speedo unit, so that might be the problem if it's not communicating with any of the controllers

yeah it's totally dead on all controllers "no response" on everything i can be bothered to try and auto scan.

You reckon i should pull the cluster apart?

I would start by unplugging/refitting the speedo connectors, if it's internal to the speedo there's next to nothing that's replaceable inside it :(

where are the connectors - I'm ok fixing mechanical things but electrics give me headaches!!

The K line from the diagnostic plug pin 7 goes to the instrument cluster on pin 25 of the Blue connector and the CAN pins 3 & 11 go to speedo Green connector pins 27 & 28 then out to the ECU on pins 19 & 20

The K line from the diagnostic plug pin 7 goes to the instrument cluster on pin 25 of the Blue connector and the CAN pins 3 & 11 go to speedo Green connector pins 27 & 28 then out to the ECU on pins 19 & 20

what do i have to take apart to get to all this wiring though.

is there any weak points - surely the actual wiring is good for the cars life.

Have you checked that fuse I listed in that other post?

Here's how to remove the speedo 6N2 Removing dash panel insert.doc

Normally the wiring is good but the signals for the diagnostics are very low current so the slightest bit of corrosion on the pins/sockets can stop the signals, so removing & refitting the connectors on the speedo might just clean them sufficient to allow the signals

Have you checked that fuse I listed in that other post?

Here's how to remove the speedo 6N2 Removing dash panel insert.doc

Normally the wiring is good but the signals for the diagnostics are very low current so the slightest bit of corrosion on the pins/sockets can stop the signals, so removing & refitting the connectors on the speedo might just clean them sufficient to allow the signals

thanks for the info - i took every single fuse out and checked it when the problem first arose, are there any other simple checks i can do to rule things out?

The only thing you can do is a continuity check from the 16 pin diagnostic plug to the pins mentioned on the speedo plugs, if they are good and removing/refitting the plug hasn't cured it then it's a new speedo unit

The only thing you can do is a continuity check from the 16 pin diagnostic plug to the pins mentioned on the speedo plugs, if they are good and removing/refitting the plug hasn't cured it then it's a new speedo unit

ok i'll pop the steering wheel and speedo unit out fettle and replace + continuity test the pins you mention.

do vw still do the wire repair kits?

Before you go dismantling any more stuff, it may pay to visit a garage and see if they can scan the car for you (+/- a fee) using their equipment.

PoloD.

Yes the wire repair kits are available from VW/TPS

Before you go dismantling any more stuff, it may pay to visit a garage and see if they can scan the car for you (+/- a fee) using their equipment.

PoloD.

as a final resort i will, but i need the diagnostics fixed really, i like to scan it regular to keep on top of things.