Location of airbag control module

[GeoffreyA]

Have a no signal/no communication issue (fault 01321) to the airbag control unit so It could be the control unit itself at fault or the power to it. My question is where is the control unit on a manual 2006 3.2 right hand drive Quattro? Was told it was under the centre console - couldn’t find a definitive answer online for the C6 but on dismantling the centre console it isn’t there! Phoned local Trades Parts Specialists for a quote on new unit and also asked where it’s located - they said under drivers seat but before I take any more of the car to bits could anybody tell me for sure where it is?
Many thanks - first post.  

[Magnet]

Hello Geoffrey, 

Welcome to the forum.

Sorry, but I cannot give you an answer to you query. However, a common trouble spot with such issues are the connectors under the seats (dust etc.). Might be worth wiggling and spraying these, assuming you haven’t already done so. 

Perhaps you could let the forum know whether that has solved it or not, and particularly if you get advice elsewhere on where the control unit lives.

Kind regards,

Gareth. 

[GeoffreyA]

Thanks Gareth - will try that and if it works will update the forum. I'm hoping it's a wiring issue and not the control unit as a new one from Audi is £600!

I'm also going to look at the relays as yesterday the fault cleared itself momentarily so if anybody knows which relay feeds the airbag control unit could they let me know. Probably one of the relays under the bonnet as I also know water can get in there when the water drains block.

[GeoffreyA]

Just for the benefit of others I am posting details of the location of the airbag control unit on a manual A6 C6 (2006) UK saloon and also the solution to my problem.

The unit is bolted onto the transmission tunnel behind the gear lever and between the seats. You cannot see it even when the centre console has been partially dismantled because it is under both the rubber car soundproofing and the plastic ventilation/heater tunnel that runs down the length of the centre console. 

It's a pain in the **** to get to but for those that need to test or replace this unit my advice follows but first some info on how I solved my issue. It started with a parking brake and airbag warning message and lights on the dash coming up. I could operate the electronic parking brake on and off manually but it would not auto release. This quickly escalated to a full Christmas tree of lights on the dash warning of ABS, ESP and parking brake/brake faults. The car would still drive but none of the systems were active. The car had been analysed by an independent Audi specialist and showed a fault code 01321 that meant there was no signal/communication with the airbag control unit J234. There was also fault code 01316  showing a parking brake issue. Turns out both were related. The garage advice was "Further investigation needed to check voltages to and from the airbag control module". The independent was happy for me to dismantle the car and expose the airbag control unit for them to test it. All the advice on the internet is not to try and test it yourself as you could inadvertently trigger any number of airbags. After I'd spent hours  finding/exposing the airbag control unit I thought I'd study all the fuses and any related relays to see if there was possibly an issue. I'd previously discounted a fuse because the problem had, on a couple of occasions, self righted so if a fuse had blown how could that happen? How wrong I was - I could have saved myself hours of research and dismantling had I done the fuse check earlier. There are three related fuses - number 10 (airbag) on the brown fuse strip on the passenger (UK) side of the dashboard, fuse F7 (parking brake) in the boot jack compartment and finally fuse 23 (parking brake) on the drivers side of the dashboard. Here is a really useful link to all A6 C6 relays and fuses. 

https://fusesdiagram.com/audi/fuses-and-relay-audi-a6-c6.html

My issue was with fuse 23 and almost certainly a 'one off' but it does send out a message to check the bl**dy obvious first before assuming that something more serious is amiss. I'd had a dash cam professionally fitted over a year ago and the correct ‘piggy back' fuse holder had been used to tap into an 'ignition live' source. 

The fitter had chosen fuse 23 and for some reason over a period of time the new fuse holder had worked loose. My theory is that the spades on the new fuse holder aren't quite long enough so it wasn't in that tightly to start with. Bumps/potholes etc must have gradually dislodged it but only on one side so the dash cam was still picking up a live feed but the parking brake was only getting an intermittent contact originally and then none at all. I know the fitter and he was amazed because that to his knowledge it was the  first ever instance of it happening. From my point of view hindsight is a wonderful thing but happy to know it was a no cost fix rather than having to potentially replace a very expensive airbag control unit.

If you are still with me here's how to access the airbag control unit J234.

First dismantle the front part of the centre console following the advice in this YouTube video.

https://youtu.be/SH1PrInREi4

Very good but you don’t need special tools to remove the rear centre console vent - two bent wire coat hangers did it for me. 

You then need to remove the light coloured plastic console 'skeleton' starting by taking off the three press on carpet clips each side. 

There are two torx screws at the back of the 'skeleton' two at each side and two at the top front. You also have to undo the four 10mm nuts that attach the metal frame to the transmission tunnel at the rear of the 'skeleton'. 

You then have access to the plastic heating/ventilation tube that runs from front to back of the console. This however won't come out until you take out the four bolts around the gear lever and the two bolts front and back of the gear lever to drop the black metal plate out of the way. Some tugging and persuading will then enable you to remove the tube. Peel back the soundproofing and there is the airbag control unit!

Apologies for the length of this post but hope it will help at least one person in some way! 

[Magnet]

Hello Geoffrey, 

Many, many thanks for coming back and letting the forum know the resolution to your issue. Such feedback really is invaluable, and the in depth detail makes it even more useful. 

Piggy back connections can be a pain - and I have ‘a thing’ about crimp connections (possibly nothing to do with this) - I just don’t trust them. Shorter than desirable spades on replacement fuses =  x number of additional fuses being possible from a set length. Where do you find consistently good quality aftermarket components these days?  OK things are cheap, but.....

Anyway Geoffrey, you must be understandably pleased with the positive outcome. All very much justified, but remember you didn’t do it on your own - it dependent on the assistance of your good pal Percy Verance. He’s been a great help to me on many occasions. 

Many thanks again and kind regards,

Gareth.