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1996 SL500, 2000 E430
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Discussion Starter #1 (Edited)
Please excuse the long title but I was doing this for future Google’ers.

I’ve seen plenty of titles like “need help fast”.

Really helpful for those googling.

i’ve had this problem for some years and I thought I’ve solved it in the interim

Brake light bulb out light would go on upon application of the brake pedal

I would check the rear brake and sometimes the light was working and a few times it was out.

But the bulb out indicator kept going on for years

I put new bulb carriers in, bulbs and it seem to solve the problem only to come back

Had a marginal battery and replaced that and it seemed to be gone for some weeks only to return

Well I went to see my friend Ernie who has an independent shop and he was telling me why this happens.

Look at these two photos and you will see plastic pins pressed in-the small circles

And with the brake light on over time the extra heat-Ernie told me how much wattage is on there generating more heat-it melts the head on this pin that holds the conductor plate firm.

Ernie gave me a far better technical explanation of which it escapes me

But the loose pin affects the electrical conductivity

I thought I would go to pick N pull and find another light which seemed good

$18 vs $250?

Brought at home installed it only to notice that same pin was broken and the plate was even looser.

Ernie said you can put LED lights in-he showed one to me-but with the reduced wattage it will still trigger the warning light

so you solve the heat problem but still have the stupid bulb out warning.

So I’ve bitten the bullet and ordered two new tail lights

Hopefelly they’ve improved this design since it came out.

The amazing thing is having had three Mercedes I’ve had the same problem through all three different chassis and taillight designs.

On the W124 they had to reinforce the plastic in 1987 that holds the metal spring that contacts the Bulb.

On my R129, I’ve gotten the same problem occasionally and noticed I apply more pressure-meaning pull out the spring that contacts the bulb.

Ernie was saying for the R129 what usually happens is overtime that lead contact on the bottom of the bulb wears down giving the same symptoms

On the W210 he said people have tried to glue this pin back and it’s a temporary fix

i’ll bet you virtually W210 has had this problem.

i’m picking up the lights tomorrow
 

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Premium Member
1998 E320 base sedan @ 160kmiles
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7,215 Posts
This is a known problem that my car has too. I put a spacer between the melted pin and the plate used a screw to keep it where it should be. A little bit of bulb grease will help prevent corrosion on the contact surface.
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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4,343 Posts
Oh don't worry, this problem persists up all the way to W164/X164.

What I do in this case is remove tail light, sand all the surface where the pins touch, and then add a very generous glob of solder all over the mating surface. Nice even layer on the surface, and then sand it until it's approximately flat.

Then plop back in and install light bulb retainer.

Problem solved.

And yes, this works on 124 up all the way to 164. All of my 210's have had this done.
 
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W163 and General M Gremlin
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Oh don't worry, this problem persists up all the way to W164/X164.

What I do in this case is remove tail light, sand all the surface where the pins touch, and then add a very generous glob of solder all over the mating surface. Nice even layer on the surface, and then sand it until it's approximately flat.

Then plop back in and install light bulb retainer.

Problem solved.

And yes, this works on 124 up all the way to 164. All of my 210's have had this done.
Time to pull out the soldering gun for a round of preventative maintenance.
After the forthcoming heatwave.
Cheers 🍻
 
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Premium Member
1998 E320 base sedan @ 160kmiles
Joined
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7,215 Posts
Oh don't worry, this problem persists up all the way to W164/X164.

What I do in this case is remove tail light, sand all the surface where the pins touch, and then add a very generous glob of solder all over the mating surface. Nice even layer on the surface, and then sand it until it's approximately flat.

Then plop back in and install light bulb retainer.

Problem solved.

And yes, this works on 124 up all the way to 164. All of my 210's have had this done.
I tried the other way. Put solder blob on the tabs of the bulb retainer. It worked for about 8 months, then the problem re-appeared. The contacts get hot, especially the brake light (21W) contact, and if the solder you use has a lowish melting temp., it will soften up over time. Maybe higher melting point solder will last longer.
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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4,343 Posts
Solder on the retainer doesn't quite work as well as the solder on the tailight itself.

The tail light surface is not smooth, and the surface contact between it and the retainer is really quite horrible, which is why it causes so much grief and burn marks. Solder on the actual taillight and made into a smooth surface works far better.

I use leaded solder, not the non-lead ones.
 

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W163 and General M Gremlin
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3,749 Posts
Solder on the retainer doesn't quite work as well as the solder on the tailight itself.

The tail light surface is not smooth, and the surface contact between it and the retainer is really quite horrible, which is why it causes so much grief and burn marks. Solder on the actual taillight and made into a smooth surface works far better.

I use leaded solder, not the non-lead ones.
I tried the other way. Put solder blob on the tabs of the bulb retainer. It worked for about 8 months, then the problem re-appeared. The contacts get hot, especially the brake light (21W) contact, and if the solder you use has a lowish melting temp., it will soften up over time. Maybe higher melting point solder will last longer.
What solder grade are you using?
Typically, I use non-eutectic solder for situations where there is a potential high heat/melting situations. The cheaper lead or tin based for typical soldering has low MP and even when the temps get up there, this solder can lose it's strength.
 

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Premium Member
1998 E320 base sedan @ 160kmiles
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7,215 Posts
No idea. I was using the solder for electronic components. There will never be a perfect surface-to- surface contact. That is why you need bulb grease or dielectric grease to prevent corrosion on the contact points. Once the contacts start pitting, the contact resistance increases which causes more heat at the contact area. It is a bad design, as you already have additional contacts between the bulb, and the bulb retainer. It could have been worse, I suppose. They could have used biodegradable wiring, as they did in the headlight assemblies :).
 

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1998 e430
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437 Posts
like mr. boca, i put a glob of solder on the bulb holder connections. been 5 years and once or twice, i've had a bulb error that went away with a wiggle.

 

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1999 E320
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6 Posts
I had this issue for years as well. When I noticed the contact plate not completely touching the bulb socket, I simply bent the plate a bit so it was constantly in contact. Did this a couple months back and never had a problem since. (What a relief to me it was)
 
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