Bulb loses contact

Ogi

Active Member
Jul 13, 2018
67
9
Serbia
Hello,

About a month and a half ago, the dashboard started reporting to me that one of the 3 bulbs in the back left is not working.

I found that the light bulb itself was ok. As I click to open the trunk, the light comes back on. So literally the smallest possible "click" returns the contact.
After that, I closed and opened the trunk for several times - it worked. When driving, everything is fine, but it happens the next time after starting the car . It bothered me like that for a few days until I found what and how to disassemble.

Then I took out the bulbs holder, replaced the bulb, sprayed the contact spray, the holder itself, as well as the jack. A month and a half there was no problem.

Few days ago the same thing happened, this time while driving, I stopped, looked, the light bulb seemed to be working.
I turned off the car, turned it on, it worked, the warning disappeared. Same thing again yesterday, while driving I turned on the lights to check and the warning light came on. I came home, parked, got out, looked, the light bulb was working. So now it's a little different, it also happens while driving, but it seems to lose contact and come back immediately.

I went to some elderly electrician across the street, old school, I can see that he is too lasy to even to speak, not to work. I barely got him to take off the bulbs holder to look. He looked at the jack, said everything is ok. He sprayed the jack with WD, tampered a little with the place where the light bulb is inserted and said that everything looks ok there. I didn't drive long after that but right after that it worked until the i turned off the car which was literally 2 minutes after all that.

Anyway, has anyone had a similar problem?

I hear that the VW group has problems with the lights.

Thanx.
 

RUM4MO

Active Member
Jun 4, 2008
7,784
983
South Scotland
I have discovered in the past few years, that at least SEAT though maybe all VW Group brands are using cheaper contact fittings in the light fittings, and this can end up being galvanised stiff bent metal/steel in place of nickel plated spring beryllium copper contacts, this can lead to extreme pressure being applied to the bulbs and especially when this is at the end that has the rounded solder contact, it can flatten that soft material and so contact lets lost as the stiff metal contact is now not touching the the bulb contact as well as it was initially. replacing any bulbs that look like their soldered end contact is flattened should solve your problem - though if you were handy with a soldering iron, a quick heating of that flattened contact would probably reform its rounded end and make it serviceable again. Returning to using suitable materials would be a better solution for customers!

Edited to add some extra context.
 
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Ogi

Active Member
Jul 13, 2018
67
9
Serbia
Actually, it was my mistake, there was no contact problem but the bulb problem - in fact, contact within the bulb.

It was not completely gone but one part of the thread inside it was loose so when u snap it with fingers, u can see it waggles.
Electrician showed me that. I didn't know it was possible, thought it can be either ok or not ok.
I came to him, explained and showed him the bulb not working.
He just hit the light slightly from behind and the bulb started working. He told me right away it was a bulb problem and showed me the thing with the thread.

Have in mind that this can also happen.
 

Walone

Active Member
Feb 10, 2016
1,538
421
Near Heathrow
Actually, it was my mistake, there was no contact problem but the bulb problem - in fact, contact within the bulb.

It was not completely gone but one part of the thread inside it was loose so when u snap it with fingers, u can see it waggles.
Electrician showed me that. I didn't know it was possible, thought it can be either ok or not ok.
I came to him, explained and showed him the bulb not working.
He just hit the light slightly from behind and the bulb started working. He told me right away it was a bulb problem and showed me the thing with the thread.

Have in mind that this can also happen.
By 'thread' I presume you mean the filament?
 

Ogi

Active Member
Jul 13, 2018
67
9
Serbia
Hah, i used google translate for that word. :)

I mean that tiny little thing in the bulb itself (this wrapped up line in it - it looks a bit different in 5W5 bulb).

1668430786684.png
 

RUM4MO

Active Member
Jun 4, 2008
7,784
983
South Scotland
So taping that light was just arc welding the filament back to its post in the bulb, but not very successfully. We used to do that to a rather special bulb in a test jig at work, it did keep things “going” until new bulbs could be sourced when production support let us down!
 
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