Audi A4 B6 interior lights not working

[Jizzle]

Hi peeps
My interior lights have just stopped working. Don't work when the doors open or by any of the light switches I have check the fuse box all fuses are good and bulbs seem fine.

From my searches this could either be an issue with the ccm or something in the door mechanism.

Any advice would be appreciated.
Cheers

[JBrookie]

If it is the door mechanism lock the doors and if you can open the doors from the outside the mechanism is bad. Depending on what door it is lots of guys have them forsale in the classified section on cars they are parting out. I have a front right door mechanism that I ended up not needing if you need that one just PM me.

[Jizzle]

Thank JBrookie
The door locks normally from the outside, so im assuming its not the door mech i did manage to do a VAG-COM scan. Fault with B+ on ccm, but all windows/alarm and sunroof functions work, so Im a bit stumped on this one,
cheers

[mikethebike3]

Hi Jizzle

I have EXACTLY the same problem on my A4 Avant 1.9tdi '03 and I've spent a LOT of time on this!

Since ALL the internal lights don't work (including, crucially, the glove box light), I believe now it can only be a problem inside the CCM, or with pin 4 of its 12 way connector which carries the +12V to the internal lights. To support this, it seems that the CCM relays on a number of German cars (including VW's, Audi's and BMW's) can fail, either by sticking closed or by high contact resistance. I've checked all my fuses and bulbs and they're OK. I've already extracted the CCM (it's under the LHS front carpet), and shortly afterwards miraculously it started to work, but when I put it all back together it lasted about 5 minutes before failing again!

Next step is to re-extract and open up the CCM and test/replace the interior light relay.

I'm just curious as to whether you sorted yours out and, if so, what you found.

Thanks

Mike

[B6A4Dave]

My car is weird like this too...my driver side floor light doesn't work...but my rear's work...

In for the solution..

[mikethebike3]

My car is weird like this too...my driver side floor light doesn't work...but my rear's work...

In for the solution..

Sorry Dave, my symptoms are different in that ALL the interior lights are out (and I don't have footwell lights anyway), but I can give some pointers.
According to Elsawin the footwell lights are all individually switched by the CCM, presumably according to which door is opened. So that's 4 separate feeds from the CCM (LHS front is a red/green wire from the 16 way connector (pin 6) to the light), and from the other side all the footwell lights are commoned at connection point A29 in the "dash panel wiring harness" wherever that is, before going to F2 (5A) in the fuse box.
Of course it could also be the bulb or a failed component in the CCM.
Good luck!
Mike

[mikethebike3]

Significant progress on my interior lights problem (i.e. none of them worked).

I've extracted the CCM PCB (its an 8E0 959 433 BC):



... and done some reverse engineering to try and understand what's going on, all the more difficult as the fault is intermittent, but getting worse as time passes.

A simplified version of my scruffy drawings appears below:



It turns out that the current to the lights passes through the contact of a small 12V relay on the CCM board, under control of the CCM CPU. This gives the +12V output that's missing from the car when the fault shows itself, but could still be a faulty lead, connector contact, dry joint or a number of other failures. Eventually, however, I was able to measure 11.5V across the relay coil WHILE THE FAULT WAS PRESENT, i.e. when the +12V out was missing! This points to a faulty relay, not with 100% certainty, but not far off!

The relay in question is a NAIS (now Panasonic) CP1-12V, bottom right in this piccy:



Datasheet here http://datasheet.octopart.com/CP1-12...eet-109908.pdf

I found a source of these from an eBay seller in Canada here http://www.ebay.ca/itm/10-pcs-NAIS-C...-/120920560173 at a great price so I've ordered some immediately. Meanwhile a quick search in the spares box revealed a 12V high current relay small enough to go inside the CCM case and so I fitted it in carefully. Early signs are that it's effected a complete cure and my interior lights are now working just as they should, but of course when the proper relays arrive I'll fit one of them. Despite the apparent success, I won't believe it's 100% OK until it's been working for a week or two but so far the signs are very good.

Note that this is just relevant to my own 8E0 959 433 BC CCM from my 2003 A4 Avant 1.9tdi, it may be similar to others but I'm no expert in this area!

Hoping that this'll help other forum members, it certainly beats buying a replacement CCM!

Mike

[mikethebike3]

As a postscript, interior lights are working well enough for me to perform an autopsy on the failed relay just to see what it's like inside.
So, 5 minutes with the Dremel and we have two final piccies (apologies for the quality, the whole relay is only 12 x 13 mm):



This is the unused normally closed contact in original shiny condition (held open with a tiny screwdriver out of shot), and



... this is the normally open contact, badly pitted and hardly surprising it didn't feel like passing current.

Mike

[Jizzle]

Hey mikethebike3
Thanks for posting up your findings. I still haven't fixed mine yet. Great to hear you had some success. I will pull my ccm out soon and see if I have the same issue. Cheers

[tedbrefflon]

MiketheBike3 - you're a star mate. Thanks for the diagrams/pictures and write up.

[mscottdemarco]

Thank you. I pulled my CCM out, tested it and confirmed the same findings. Ordered the relay.

[WB650]

Yeah I disconnected the siren b/c the internal battery was dying, couldnt' get trim all the way off so I yanked on the plug and ended up pulling out one of the wires from the connector and stupidly stuffed it back in the area. After this is when I noticed none of my dome lights work. My front footwell lights and and occasionally the rear passenger footwell will work. Figure something shorted and caused and issue with the CCM. A shop has had Vagcom hooked up and he couldn't figure it out