Check left rear sidemarker lamp BUT two lamps don't light
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Joined: Jul 2012
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2010 MB C300 Sport
Check left rear sidemarker lamp BUT two lamps don't light
Just bought a 2010 C300 (I'm a newbie to MB) and as we were driving off we noticed the top half of our left rear tail light was out so we grabbed our salesman. He said "oh maybe just a loose bulb" and tapped on the outside. When we turned the car back on the light was working so, yeah, a loose bulb. (note: it was 9:30pm and they had closed at 9pm)
Car is still under warranty so we had no real worries.
Except, it wasn't a loose bulb.
We got home and intermittently we get a "Check left rear sidemarker lamp", but almost always at night, during the day it's rare to see it. (duh: light isn't checked until it's used is it?)
But, it's not only the SIDE MARKER LAMP, it's also the TOP TAIL/FOG LAMP that's out. But I don't get a TAIL LAMP out message at all.
Here is what people see when they follow my beautiful Mercedes:
So I thought I would reseat the bulbs and the plug and fix it. And surprise, that didn't work, so off to buy two new bulbs.
This is where I'm spooked. Replacing both new bulbs didn't fix it either AND I'm finding some possibly troubling changes. This is what I found when I opened the tail light: UNEXPECTED WIRES AND MISSING TURN SIGNAL BULB!
After market LED lights on a car with electrical problems UNDER WARRANTY.
NOW I notice the rear LED turn signals:
1. Please - need help from somebody that knows, if I bring this in to have it diagnosed and repaired has this voided the warranty? We did call and check the VIN before purchase and they said the car was still under warranty but I can't prove that if they change their minds.
2. Which LED assemblies are these, good ones, bad ones, did it take a hack in the electrical system somewhere to make these flash correctly? To clarify my question, are these just "drop in taillight LEDs" with no electrical work required (hardware swap only) OR did they require modification somewhere in the electrical system to get a error free turn signal?
3. Does it make sense that the tail lamp fails at the same time as the side marker lamp? Wouldn't I expect to get a second error for that lamp also? And yes i checked messages and there is only one for the left rear sidemarker lamp.
Maybe I'm stressing over nothing but hopefully somebody can help. A schematic would be helpful, if I knew about the LED modification.
Hey, if somebody can help me fix this then a trip to the stealership wouldn't even be necessary.
Any help would be greatly appreciated.
-Texas Hugh
PS - That's correct, I didn't mention the missing nut that's in the picture. I don't know much about cars but SURELY in 2012 they don't ground a tail light with a nut like that. But if I'm worng then problem solved. I'll try to find something to fit that tomorrow.
Car is still under warranty so we had no real worries.
Except, it wasn't a loose bulb.
We got home and intermittently we get a "Check left rear sidemarker lamp", but almost always at night, during the day it's rare to see it. (duh: light isn't checked until it's used is it?)
But, it's not only the SIDE MARKER LAMP, it's also the TOP TAIL/FOG LAMP that's out. But I don't get a TAIL LAMP out message at all.
Here is what people see when they follow my beautiful Mercedes:
So I thought I would reseat the bulbs and the plug and fix it. And surprise, that didn't work, so off to buy two new bulbs.
This is where I'm spooked. Replacing both new bulbs didn't fix it either AND I'm finding some possibly troubling changes. This is what I found when I opened the tail light: UNEXPECTED WIRES AND MISSING TURN SIGNAL BULB!
After market LED lights on a car with electrical problems UNDER WARRANTY.
NOW I notice the rear LED turn signals:
1. Please - need help from somebody that knows, if I bring this in to have it diagnosed and repaired has this voided the warranty? We did call and check the VIN before purchase and they said the car was still under warranty but I can't prove that if they change their minds.
2. Which LED assemblies are these, good ones, bad ones, did it take a hack in the electrical system somewhere to make these flash correctly? To clarify my question, are these just "drop in taillight LEDs" with no electrical work required (hardware swap only) OR did they require modification somewhere in the electrical system to get a error free turn signal?
3. Does it make sense that the tail lamp fails at the same time as the side marker lamp? Wouldn't I expect to get a second error for that lamp also? And yes i checked messages and there is only one for the left rear sidemarker lamp.
Maybe I'm stressing over nothing but hopefully somebody can help. A schematic would be helpful, if I knew about the LED modification.
Hey, if somebody can help me fix this then a trip to the stealership wouldn't even be necessary.
Any help would be greatly appreciated.
-Texas Hugh
PS - That's correct, I didn't mention the missing nut that's in the picture. I don't know much about cars but SURELY in 2012 they don't ground a tail light with a nut like that. But if I'm worng then problem solved. I'll try to find something to fit that tomorrow.
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Joined: Feb 2004
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From: SEATTLE WASHINGTON USA
'08 C300 Lux Barolo Red Beige Leather P2 MM 18" wheels '84 944
Just bought a 2010 C300 (I'm a newbie to MB) and as we were driving off we noticed the top half of our left rear tail light was out so we grabbed our salesman. He said "oh maybe just a loose bulb" and tapped on the outside. When we turned the car back on the light was working so, yeah, a loose bulb. (note: it was 9:30pm and they had closed at 9pm)
Car is still under warranty so we had no real worries.
Except, it wasn't a loose bulb.
We got home and intermittently we get a "Check left rear sidemarker lamp", but almost always at night, during the day it's rare to see it. (duh: light isn't checked until it's used is it?)
But, it's not only the SIDE MARKER LAMP, it's also the TOP TAIL/FOG LAMP that's out. But I don't get a TAIL LAMP out message at all.
Here is what people see when they follow my beautiful Mercedes:
So I thought I would reseat the bulbs and the plug and fix it. And surprise, that didn't work, so off to buy two new bulbs.
This is where I'm spooked. Replacing both new bulbs didn't fix it either AND I'm finding some possibly troubling changes. This is what I found when I opened the tail light: UNEXPECTED WIRES AND MISSING TURN SIGNAL BULB!
After market LED lights on a car with electrical problems UNDER WARRANTY.
NOW I notice the rear LED turn signals:
1. Please - need help from somebody that knows, if I bring this in to have it diagnosed and repaired has this voided the warranty? We did call and check the VIN before purchase and they said the car was still under warranty but I can't prove that if they change their minds.
2. Which LED assemblies are these, good ones, bad ones, did it take a hack in the electrical system somewhere to make these flash correctly? To clarify my question, are these just "drop in taillight LEDs" with no electrical work required (hardware swap only) OR did they require modification somewhere in the electrical system to get a error free turn signal?
3. Does it make sense that the tail lamp fails at the same time as the side marker lamp? Wouldn't I expect to get a second error for that lamp also? And yes i checked messages and there is only one for the left rear sidemarker lamp.
Maybe I'm stressing over nothing but hopefully somebody can help. A schematic would be helpful, if I knew about the LED modification.
Hey, if somebody can help me fix this then a trip to the stealership wouldn't even be necessary.
Any help would be greatly appreciated.
-Texas Hugh
PS - That's correct, I didn't mention the missing nut that's in the picture. I don't know much about cars but SURELY in 2012 they don't ground a tail light with a nut like that. But if I'm worng then problem solved. I'll try to find something to fit that tomorrow.
Car is still under warranty so we had no real worries.
Except, it wasn't a loose bulb.
We got home and intermittently we get a "Check left rear sidemarker lamp", but almost always at night, during the day it's rare to see it. (duh: light isn't checked until it's used is it?)
But, it's not only the SIDE MARKER LAMP, it's also the TOP TAIL/FOG LAMP that's out. But I don't get a TAIL LAMP out message at all.
Here is what people see when they follow my beautiful Mercedes:
So I thought I would reseat the bulbs and the plug and fix it. And surprise, that didn't work, so off to buy two new bulbs.
This is where I'm spooked. Replacing both new bulbs didn't fix it either AND I'm finding some possibly troubling changes. This is what I found when I opened the tail light: UNEXPECTED WIRES AND MISSING TURN SIGNAL BULB!
After market LED lights on a car with electrical problems UNDER WARRANTY.
NOW I notice the rear LED turn signals:
1. Please - need help from somebody that knows, if I bring this in to have it diagnosed and repaired has this voided the warranty? We did call and check the VIN before purchase and they said the car was still under warranty but I can't prove that if they change their minds.
2. Which LED assemblies are these, good ones, bad ones, did it take a hack in the electrical system somewhere to make these flash correctly? To clarify my question, are these just "drop in taillight LEDs" with no electrical work required (hardware swap only) OR did they require modification somewhere in the electrical system to get a error free turn signal?
3. Does it make sense that the tail lamp fails at the same time as the side marker lamp? Wouldn't I expect to get a second error for that lamp also? And yes i checked messages and there is only one for the left rear sidemarker lamp.
Maybe I'm stressing over nothing but hopefully somebody can help. A schematic would be helpful, if I knew about the LED modification.
Hey, if somebody can help me fix this then a trip to the stealership wouldn't even be necessary.
Any help would be greatly appreciated.
-Texas Hugh
PS - That's correct, I didn't mention the missing nut that's in the picture. I don't know much about cars but SURELY in 2012 they don't ground a tail light with a nut like that. But if I'm worng then problem solved. I'll try to find something to fit that tomorrow.
Apparently you have a 2010 so why the mention of 2012?
Last edited by RLE; Aug 14, 2012 at 02:39 AM.
Thread Starter
Newbie
Joined: Jul 2012
Posts: 7
Likes: 0
2010 MB C300 Sport
My owners manual shows a picture how to replace that turn signal bulb, even lists the type bulb as PY 21 W, but I DO have Bi-Xenon lights. Factory LED's? That's great! I won't mess with it anymore. It's a warranty deal. I appreciate the feedback. Whew!
The comment "surely in 2012" I meant to say out of the cars on the road today, in 2012. It wasn't worded correctly I see that now, sorry for the confusion. I don't know as much about cars as I should but I would think grounding the tail light assembly to ground for a connection would be a 1930s or 1940s thing, if it ever happened.
The comment "surely in 2012" I meant to say out of the cars on the road today, in 2012. It wasn't worded correctly I see that now, sorry for the confusion. I don't know as much about cars as I should but I would think grounding the tail light assembly to ground for a connection would be a 1930s or 1940s thing, if it ever happened.
Junior Member
Joined: Dec 2011
Posts: 30
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From: Bolton
C220 CDI Sport
Old thread but I thought i'd post up as I had the exact same problem and it bugged me for ages.
Computer was displaying a left rear side light error. My car looked exactly the same as the picture of the other car with the top section out. It really bugged me as I have a thing about symmetry...
Anyways, the top section comprises of a PY21w bulb and a w5w bulb. Ignoring the w5w, i swapped around the bigger bulb with different ones and the bulb was absolutely fine in other sockets so it wasn't a bulb problem. Got a voltmeter out to check for power on the facia plate. Power was being supplied to the w5w but no power to the PY21w. Then i started to panic as i read about replacing the SAM and the expenses involved!
Got the voltmeter out again and tested directly from the wiring harness. Followed the wires and tested the 2 sources. Both were outputting power but somehow the power wasn't getting through to the PY21w.
Left it for a few days and read up loads of threads when it hit me that i hadn't tried swapping the w5w. As soon as i replaced that, both bulbs lit up instantly! DOHHHHHHHHH!
For anyone reading this, when it says a bulb is out, check all bulbs not just one of 2...
Computer was displaying a left rear side light error. My car looked exactly the same as the picture of the other car with the top section out. It really bugged me as I have a thing about symmetry...
Anyways, the top section comprises of a PY21w bulb and a w5w bulb. Ignoring the w5w, i swapped around the bigger bulb with different ones and the bulb was absolutely fine in other sockets so it wasn't a bulb problem. Got a voltmeter out to check for power on the facia plate. Power was being supplied to the w5w but no power to the PY21w. Then i started to panic as i read about replacing the SAM and the expenses involved!
Got the voltmeter out again and tested directly from the wiring harness. Followed the wires and tested the 2 sources. Both were outputting power but somehow the power wasn't getting through to the PY21w.
Left it for a few days and read up loads of threads when it hit me that i hadn't tried swapping the w5w. As soon as i replaced that, both bulbs lit up instantly! DOHHHHHHHHH!
For anyone reading this, when it says a bulb is out, check all bulbs not just one of 2...
Senior Member
Joined: Dec 2011
Posts: 387
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2008 Mercedes C300
I had a somewhat similar issue but never had an alert on dash READ: https://mbworld.org/forums/c-class-w...ghts-true.html
