Rear dome/map lights

[Audifan]

My rear dome/map lights seems to work whenever it feels like it. As of right now it's not working when opening the rear doors. What is causing this problem? Can it be fixed? I'm guessing the light assembly is no longer available new?

[HPsauce]

I had this problem and spent ages investigating, even replacing the unit which wasn't very productive as the replacement had similar issues.
It's documented here somewhere, but your problems are probably due to dry/cracked solder joints. Mine definitely were.

Basically the solution for me was to take it apart (surprisingly easy) and IIRC open up the switch/control block and resolder the joints on the PCB inside.
It all pops open with care and clicks back together, nothing needs breaking or gluing afterwards to reassemble.

I resoldered both my units so now have AFAIK a working spare too - beige, but a bit scruffy.

[Audifan]

Thanks for the way info. I did a search on here and found your old post about this. That spare assembly that you still have, would you be willing to post pictures of it taken apart showing what and where the bad solder joints needs to be fixed?

[HPsauce]

Not sure I can find it or even know where it is I'm afraid.

That thread you found describes in the subsequent posts how to take it apart pretty comprehensively though. Those bus bars just pry out and everything else is just clipped together so can be released undamaged with care. The PCB is quite small so not many connections to fix. And it can probably be done still mounted if you prefer to only remove the busbars.

IIRC the switch itself, although I did take it apart, wasn't my problem and can be checked externally with a multimeter so probably best to leave that in one piece.

[HPsauce]

Originally Posted by HPsauce

Not sure I can find it or even know where it is I'm afraid.

But I did pop the unit out that's installed in the car. I don't want to dismantle that as it's working, so a photo is attached of the PCB with busbars in the way.

The 6 pins in a row are the socket, with 2 immediately behind widely spaced.
Then there are 7 more in a row (3 and 4 either side of a busbar socket and partly obscured in the photo).

I just don't recall which 3 are the rocker switch, but best to look at them all closely and remake any suspect solder joints.
(My suspicion would be the top left three almost hidden in the photo as the top right group of three that are visible are interconnected on the PCB - pointless for a switch!)

It's incredible how heavy and over-engineered this is for what it does!

[HPsauce]

Originally Posted by HPsauce

I don't want to dismantle that as it's working

To get at the switch unit:
1. Remove the transparent window and take out the festoon bulbs. Optionally remove the map/reading light bulbs too.
2. Lever out bus bars carefully (there are a couple of plastic lugs to push aside for the big one)

If you want to lift out the PCB and switch block it's held in by the big black plastic clips either side - very easy to push them back to release, any old blunt blade should do.

[Audifan]

Originally Posted by HPsauce

It's incredible how heavy and over-engineered this is for what it does!

Yes it is WAY over-engineered for something that is supposed to a simple light assembly.

Originally Posted by HPsauce

To get at the switch unit:
1. Remove the transparent window and take out the festoon bulbs. Optionally remove the map/reading light bulbs too.
2. Lever out bus bars carefully (there are a couple of plastic lugs to push aside for the big one)

If you want to lift out the PCB and switch block it's held in by the big black plastic clips either side - very easy to push them back to release, any old blunt blade should do.

Thanks for the info. I currently have mine taken out of the car and will carefully take it apart.

[Audifan]

Here is a picture of my rear light assembly taken out of my S8. Oh my gosh I hate rust!


I carefully pulled out the bus bars and light switch.


Here is a close up picture of the light switch circuit board.


Do I need to separate this green circuit board to fix the solder joints? If so, do I just carefully pry up the circuit board?

[HPsauce]

NO! All the joints are in front of you. Just make sure they are separate from each other and resolder as needed. Some of those look less than ideal.
There is a clear short circuit bottom left for a start!

I usually scrape away contamination with a sharp point and after soldering apply some nail varnish to seal (ooooh missus!)

[Audifan]

Ah ok. I'll see if I can get my friend to help out with this as he's more experienced with type of stuff then me.