Bought a VRS at the start of February and had the head unit changed (professionally) soon after. A few weeks later the airbag warning light came on and the Skoda dealer is saying that there is no reading from the diagnostic system and that this has been caused by changing to a non-standard head unit.

Is this likely? to my untrained mind I can't see what would need to be changed electronically in respect of power feeds etc. Any advice gratefully received before I go and see what the car stereo dealer has to say about it.

Thanks

The OEM HU does talk to the ECU, but I can't see it refusing complete communication because of after market unit.

Did the dealer try disconnecting the HU?

It is possible that the aftermarket head unit is causing a problem if the K-line and/or CAN bus wires have been left wired into the harness. They should be disconnected and isolated.

I remember reading in past threads (I believe) that if you hook up the blue "powered aerial" wire incorrectly (and apparently it is/was quite common to do so) then the dealers diagnostic equipment can have problems communicating with the ECU, to the point the diagnostic reading equipment can actually be damaged as a result. I cannot be 100% sure this is the case (that the blue wire was the cause), but you might want to do a search, as I do remember coming across this when I was looking for info on installing an aftermarket HU. I even remember reading some dealers were refusing to connect to the HU when they saw aftermarket HU's were installed, until they could be sure the connections were made correctly. I think it has something to do with power being sent along the K-line, when it shouldn't be, but I don't claim to be an expert on such things. Hope this helps in some way, you might want to try a search in the ICE section.

Ooops, shark_90 beat me to it! I guess my post was too long-winded.

Other people are right, it usually ends up that you're powering the Kline which blocks communication.

One car we had here, the headunit had to be disconnected, the moment it was, diagnostics could then communicate with the car.

Kev

fairzo I'm in Mansfield if you want me to have a look at it for you.

when I fitted a new blaupunkt HU to my octy I was very careful to make sure that I disconnected the K line but I have subsequently found that I have to take out the fuse to radio before vagcom will work with the car. I followed the instructions on the ross tech website and checked the voltage on the diagnostics port and that was fine.

So obviously something strange is going on in the wiring somewhere that is blocking communications but not putting 12V down the K line fortunately. I just haven't had the time or the enthusiasm to remove the radio and ferret about with all the wiriing back there.

Thanks for all the help - so there's obviously something wrong and I wouldn't have known what to search for.

Shark_90, thanks for the offer. I'm only about 15 miles from Mansfield. The car is back into the Skoda dealer next Tuesday and they are happy enough to replace the new HU with the original and then sort out the airbag problem under warranty. They won't put the non-standard HU back in though. I've asked if they'll give me a note of what's wrong and then I was going to go back to the stereo dealer. Lost faith in them really though so ok if I get back in touch at the end of next week?

Yes of course, just give me a shout. And if you're local make sure you come down to the East Midlands meet at the end of the month, on the A38 near Mansfield

Ok will keep in mind thanks.

Shark_90 have sent you a PM