2005 CLK500 Tail Light Issue - Need Help
Thread Starter
Newbie
Joined: Jul 2019
Posts: 6
Likes: 0
From: Venice, FL
2005 CLK500
2005 CLK500 Tail Light Issue - Need Help
Hello everyone! I just picked up a 2005 CLK500 about a week ago, and noticed that my rear lights do not come on with the head lights. The rest of the lights in the rear do work though (reverse, brake, and turn signals). The monitor display said the 3rd brake light is out, but it works fine. I checked the bulbs on both sides, and they look fine as well. I was told that it might be the rear SAM unit going out. If it is the SAM unit, am I able to program a new one? Or will I have to have the dealer program it? Last question. Could it be anything else other than bulbs, or the rear SAM unit? Thank you guys for any help! 
Member
Joined: Aug 2010
Posts: 223
Likes: 43
From: PA
2016 E350 Sedan SPort
Interesting- I just replaced rear standing lamp bulb 4 on right side;
warning on dash said tailight out and backup being used
It e=was very hard to see that the bulb was bad-- the wire is tiny and the bulb is small;
Advanced auto couldnt find the little bulb but they did have it -Sylvania 5007
4 is standing lamp (parking)
side marker,
MER-02703 7260101 Osram&Bosch R5W Sylvania 5007
I started with a bad left brake light- changed and it was fine-
so decided to change all the bulbs on both sdes-
couldn't fond bulb 4-- the small one.
Then the taillight warning went on for right side--etct etc
Till fnally found the bulb and changed-- everything fine now.
So- not sure that helps on the 3rd brake light warning- mabe change all the bulbs in the rear assembly and see if it helpe.
Not sure how to change the 3rd brake light on the trunk.
Mabe start with that; maybe Rudney knows vs my trial and error.
warning on dash said tailight out and backup being used
It e=was very hard to see that the bulb was bad-- the wire is tiny and the bulb is small;
Advanced auto couldnt find the little bulb but they did have it -Sylvania 5007
4 is standing lamp (parking)
side marker,
MER-02703 7260101 Osram&Bosch R5W Sylvania 5007
I started with a bad left brake light- changed and it was fine-
so decided to change all the bulbs on both sdes-
couldn't fond bulb 4-- the small one.
Then the taillight warning went on for right side--etct etc
Till fnally found the bulb and changed-- everything fine now.
So- not sure that helps on the 3rd brake light warning- mabe change all the bulbs in the rear assembly and see if it helpe.
Not sure how to change the 3rd brake light on the trunk.
Mabe start with that; maybe Rudney knows vs my trial and error.
Member
Joined: Aug 2010
Posts: 223
Likes: 43
From: PA
2016 E350 Sedan SPort
IIf its all the taili lights out- then change bulbs 4 & 5 and then check
The rear panels can be tough to take out and remove- have to twist them slightly to get out
search in this forum for "third brake light"
Mine was doing this, so I removed the light from the trunk and took (i.e. cut) the lens off. I was expecting to find bad solders, broken wiring, or corrosion, but it was all just fine. I use silicon sealant to reattach the lens, then reinstalled the light, being careful not to over-tighten the nuts - they only need to tighten enough to stay in place. After that, no more errors. All I can figure is that the light was bolted too tightly in place and caused an intermittent short.
e.g.
The rear panels can be tough to take out and remove- have to twist them slightly to get out
search in this forum for "third brake light"
Mine was doing this, so I removed the light from the trunk and took (i.e. cut) the lens off. I was expecting to find bad solders, broken wiring, or corrosion, but it was all just fine. I use silicon sealant to reattach the lens, then reinstalled the light, being careful not to over-tighten the nuts - they only need to tighten enough to stay in place. After that, no more errors. All I can figure is that the light was bolted too tightly in place and caused an intermittent short.
e.g.
Thread Starter
Newbie
Joined: Jul 2019
Posts: 6
Likes: 0
From: Venice, FL
2005 CLK500
It's just the rear running lights I think they're called? Ones that are supposed to come on with the headlights that don't come on. All of the other lights in the rear work fine.
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MBWorld Fanatic!
Joined: May 2008
Posts: 1,250
Likes: 21
From: Los Angeles, CA
Supercharged CLK500,ML500,S580
I bit the bullet and payed the $120 for a new third brake light and the warning went away. There is probably something broken internally in the light causing voltage issues.
Before you pay $300+ for a new rear SAM and programming, I recommend to replace the 3rd brake light with a new unit and see if the problem goes away.
