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Discussion Starter #1
Hi all
Just had to post my latest result. My problem was that the dipped beam (no other bulbs/lights) was lighting up on ignition2 or engine running! If just ignition1 -you could turn on the sidelights as expected, then, if you go to ig2 only (don't start engine), that lights up the dash lights and turns on the ignition (can hear the usual engine elecs whirring away, as well as dipped beam!).

The car started and drove fine, but just always had dipped beam bulb lit up.
Main beam bulb worked as expected too, either on the flash stalk or pushed forward.

So I took the headlight switch out completely (along with the fuses block) by removing the lower panel, and removing all four plugs from the back of the headlight switch - two seem to be for the headlight switch specifically, and the other big ones with multi pins one with the grey and one with the black fold over safety clips are for the fuse block.

I took the switch outer housing off by unclipping all of the catches, and carefully prised off the switch knob to enable the housing to come free. Once in there, there is a circuit board with lots of soldered pin connections, and yup you guessed it, a couple of them were dry - just like in the K40 relay - see other post for that happy outcome.
All of the soldered pins were single except two which were each double, i.e. close pins soldered together and therefore were joined. One of these doubles was at each end of the board, and one of them was dry - exposed pins more than the others, degraded solder etc, all other pins were all good. So I re-soldered the dry double one, fitted it all back together, and hey presto, job's a good'un mate, lights all work absolutely fine and as expected.

It's those pesky dry joints again! Who would have thunk it, but hey, that's the way these cars are it seems, and I'd rather have relatively easy fixes like these than blown engines or noisy gearboxes or whatever. And presumably, once you have been through all of these types of issues, they shouldn't come back - providing you did a good enough job of your soldering and re-assembly. I just love fixing the cars, one of the best feelings, achievement etc. So good luck guys and gals, and hope you find this useful - smiley face (how do you get those on these posts :)
 

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Premium Member 2001 SLK200K/2001 SLK320
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@porky

That could be useful as they are known to fail and have you seen the price of that unit? - stupid expensive!

I've got one in my garage that I've been meaning to take apart for about 5yrs but I just haven't got around to it .. yet :)

Have you got any photos?
 

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Discussion Starter #3
No sorry bud, but's it's all nice and simple once you get into it and comes apart, easy to remove and self evident, just be nice and gentle with the plastic fixings, the clip-together points, and be patient. The soldering is as anywhere else on these boards, 99% fine but it's the odd one that causes the problems. Much better to fix than to waste loads of money replacing. Save that for upgrades :) Good luck
 

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Premium Member 2001 SLK200K/2001 SLK320
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No sorry bud, but's it's all nice and simple once you get into it and comes apart, easy to remove and self evident, just be nice and gentle with the plastic fixings, the clip-together points, and be patient. The soldering is as anywhere else on these boards, 99% fine but it's the odd one that causes the problems. Much better to fix than to waste loads of money replacing. Save that for upgrades :) Good luck
Bit late for that advice, I replaced it years ago with a 2nd hand unit that I found on eBay for £100 :surprise:

Replaced because it made my ignition permanently live, all dash lights on ala key in position 2 and engine still running even tho I'd taken the key out - go figure :confused:
 

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Discussion Starter #5
mm crikey - I wouldn't be surprised by doing this to have such an effect - there's so much switch connectivity going on with a circuit board. Always worth taking these things apart and having a good old look at it. Now that we know how these cars can be vulnerable, it's a case of applying the knowledge and necessary skills - via solda!
 

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Premium Member 2001 SLK200K/2001 SLK320
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mm crikey - I wouldn't be surprised by doing this to have such an effect - there's so much switch connectivity going on with a circuit board. Always worth taking these things apart and having a good old look at it. Now that we know how these cars can be vulnerable, it's a case of applying the knowledge and necessary skills - via solda!
Hmmm .. did it look anything like this? :
 

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Registered 2002 R170 SLK V8 5.0
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Hi,

I am increasingly seeing more and more dry joints on modern vehicle electronics, things like Cars with Immo in Dash Cluster, that don't start (think VW's Fords etc) ;)

The reason is Mfrs are using un-leaded tree hugger solder which makes a brittle joint, I bought up a couple of dozen reels of leaded some years ago, and always use a dab of active flux ;)

HTH,

Cheers Dave
 
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