Faulty Rear Interior Light Repair

wilco184

Member of the year 2015
Hello.

I noticed recently that when opening any of the doors, only the front interior lights illuminated. The rear lights would illuminate only when the front light was set to be always on using the rocker switch, which is different to other cars and certainly does not seem conventional. I began attempting a repair by checking the wiring to the front light, but all seemed well. I then removed the rear light by gently prising it out, it is held in by 4 spring clips and simply pulls out from the headlining. Again, the wiring to the light seemed fine, leading me to the possibility of the rear light unit itself being faulty.

I examined the joints on the PCB on the back of the unit with a magnifying glass to see a small ring around a soldered joint, which seemed to be a dry joint. I have circled the offending joint on the following photo.

Rear Light PCB.jpg

To fix this, I heated the joint with a soldering iron and added a little solder. I then put the light back in the car, and it worked exactly as it should. When a door is opened, both the front and rear interior lights now illuminate. I checked our other A2 as well, just out of curiosity, and I found that this rear light was faulty in the same way, and that the exact same solder joint had failed! Both cars had the same problem. I also repaired this, which also now too works perfectly.

I'm not sure if this joint is a known weakness as a forum search revealed nothing, but it's a simple fix if you have a spare 5 minutes!

Regards,

Matt.
 

scott

Member
Thank you, just wish it was sooner as I bought a replacement one a couple of months ago! Which now has the same problem! With both units I noticed if you push firmly on the switch in the central possession it will work again for a little while. Thanks to you I can now fix it properly.
 
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dan_b

Member
I had the exact same failure symptoms on mine. Although didn't attempt to repair it with a soldering iron :)
 

daniel_se

Member
I have the exact same symptoms, rear light will only come on if the front light is switched to I. Will try to pry it lose and check the joint on the back, dont think I have used a soldering iron in 20 yrs though :)

I also have a dead interior light in the boot. After some searching the forum I have come to the conclusion that it could be the microswitch in the hatch locking mechanism that is failing, and that it could use some WD40 and some manual opening ans closing a few times. Sound reasonable?
 

wilco184

Member of the year 2015
I have the exact same symptoms, rear light will only come on if the front light is switched to I. Will try to pry it lose and check the joint on the back, dont think I have used a soldering iron in 20 yrs though :)

Best of luck, Daniel. Please keep us informed regarding if this works for you! :)

I also have a dead interior light in the boot. After some searching the forum I have come to the conclusion that it could be the microswitch in the hatch locking mechanism that is failing, and that it could use some WD40 and some manual opening ans closing a few times. Sound reasonable?

That sounds reasonable, yes. Please check that it isn't just the bulb has blown or has come out of its socket, but otherwise WD40 sounds like a good place to start. Personally, I would recommend 'Servisol Super 10', which is a switch cleaning lubricant - perfect for what you're trying to do. It's pretty inexpensive and works well with switchgear, although I've near used it personally on the A2.

Some other threads on the forum have suggested however that even if cleaning fixes the problem, it may well return in the near future. An example of this is here. http://www.a2oc.net/forum/showthread.php?17657-Tailgate-microswitch Cleaning is certainly worth attempting though, in my opinion.

Regards,

Matt.
 

fbi

Member
Mine has the same symptoms aswell.
I had a look, but couldn't find any cracked welding. I thought there was some play in a copper lamella, but no, the problem hasn't gone after reassembly. Apparently, it sits in the switch itself, since when I "play" a little with it (0-1-door-...) the light comes on.
Is it possible to open the switch and fix it ?
It looked like a "sealed" component to me, but I should have another look at it to make it sure.

Fabrice
 

daniel_se

Member
I have now checked my interior lights. The boot one appears to be working, using my multimeter it has power so will try to replace the bulb.

On the rear inteterior light it has the same symptoms as above, I can use the rocker switch in the front to get it going in the back but it does not come on when opening the doors as it should. I have tried pressing it in the center but nothing. When I look at it the joint described earlier seems rather black, I havent used a soldering iron in years, do I just put some new soldering on there? It looks like the same joint right?

image1.jpg
 
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Just re-melting the original solder should do the trick if it is a dry joint. You can add a little, but don't overdo it. And yes that looks the same pin as above.

Chris
 

Sootywg

Member
A little soldering flux would help as the black oxide wil prevent the solder ' wetting' the joint.

If you can remove any obvious oxide with a sharp point it will also help

Geoff
 

daniel_se

Member
Brilliant!!!

Shaky hands and squinting with bad eyes, but I got the soldering done and the rear light now works a charm. Many thanks, would never have found that without this thread

Also changed the bulb in the boot, but nothing there. My multimeter shows a current in the connector but very faint. Might be the microswitch in the boot, I understand that is menace to get som wd40 in there?

Daniel
 

timmus

Member
Brilliant!!!

Shaky hands and squinting with bad eyes, but I got the soldering done and the rear light now works a charm. Many thanks, would never have found that without this thread ��

Also changed the bulb in the boot, but nothing there. My multimeter shows a current in the connector but very faint. Might be the microswitch in the boot, I understand that is menace to get som wd40 in there?

Daniel

This is indeed a brilliant thread.

Daniel,

If the boot lock microswitch isn't working, not only will the boot light not come on, but the display in the instrument cluster also won't indicate that the boot is open. I have tried reviving these microswitches with a spray of contact cleaner in the past and have only ever had moderate success; after a few weeks or months, the fault has always returned. Replacing the catch is generally the best long-term option.

Cheers,

Tom
 

alanb

Member
Got round to looking in to this. Switch out, bulbs ok. Soldering iron on. Few seconds on the joint in question. Back into the car. Bingo! Sorted.
So pleased you started this thread as the problem has been bugging me for ages!

Many thanks.
A
 

daniel_se

Member
P
This is indeed a brilliant thread.

Daniel,

If the boot lock microswitch isn't working, not only will the boot light not come on, but the display in the instrument cluster also won't indicate that the boot is open. I have tried reviving these microswitches with a spray of contact cleaner in the past and have only ever had moderate success; after a few weeks or months, the fault has always returned. Replacing the catch is generally the best long-term option.

Cheers,

Tom

You are right, the display does not indicate boot open so definitely the microswitch. But how can I clean it? Do I have to remove the interior on the trunk? Seems like alot of work just to get the boot light going.....

Daniel
 

wilco184

Member of the year 2015
P

You are right, the display does not indicate boot open so definitely the microswitch. But how can I clean it? Do I have to remove the interior on the trunk? Seems like alot of work just to get the boot light going.....

Daniel

Hi Daniel,

I haven't completely this task personally, but it may be possible to clean the microswitch from the lock as you see it with the trim in place, the lock mechanism is tight, but there looks to be a small gap at the top of the catch leading into the main 'cavity' of the lock, I won't promise putting contact cleaner in here will work, but it certainly seems worth a try. Ideally though the trim around should be removed to clean, there are multiple holes in the lock casing where cleaner could be sprayed in, if I recall correctly.

Regarding it being a lot of work for the boot light to work, the lack of an indication on the dash also means that its possible for the boot to be not properly latched despite looking closed. Ensuring the boot is properly closed may be something to be careful of without a functioning indicator.

Regards,

Matt.
 
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