Tried Osram LED 5W5 501 bulbs in boot lamps .... neither worked :(:(

Submariner1

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I bought these from an eBay seller claiming to be an official Osram Partner.
Neither worked! :(:(

So I then tried the original bulbs, both didn't work, but they did before.
Here is the weird bit:-
I had to turn the side lights on and off , and then the original bulbs worked perfectly again.

These Osrams look like they fit perfectly. Note all the other MB lights work perfectly.

Thinking this was probably an odd car glitch, I tried the Osram LEDs again. Both Didn't work.

So I tried the original MB ones again, same oddity. Turned the sidelights on and off, and the MB ones work perfectly, with or without sidelights.

Shut the boot 5 x ... all good, they go on and off as they should with the MB original bulbs.

I then tried the free set of 5W5s that came with my Phillips White Vision cornering H7. And they worked perfectly. So imo there is nothing wrong with the car.

so the question is
1. Can one test an LED bulb with a multimeter? I.e. check resistance or dont LEDs work like that?
2. Could there be something in the Mercedes circuit, that prevents the car powering a 1W LED. Instead of a normal 501 5 watt bulb? [I don't think there is]


Note: If I take one or even two of the normal MB 5W5 bulbs out, the other one still works, and there are no canbus warning messages like a failed bulb. If I later put one or both back .... it or theynjust work.
So IMO the boot lights are not on the Canbus warning system.

3. Is it worth getting a link off the Osram site to an officail reseller, like Power-bulbs, and trying again with LEDs?
I.e. I just got conned with rubbish fakes

Appreciate your views, but Sadly I can’t do any suggested testing, as the car is now at the Dealers (sorting out another not connected issue).

Note I have upgraded 6 of the front bulbs ... all perfect. But they were bought from Powerbulbs.
 
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EmilysDad

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....

So I then tried the original bulbs, both didn't work, but they did before.
Here is the weird bit:-
I had to turn the side lights on and off , and then the original bulbs worked perfectly again.

......

That's the case when I've replaced any lamp/bulb on my car ... CANbus electrickery :)

I recently removed number plate light bulb just to see what type it was. Refitted it & it lit :confused: turned the switch off & on again and order was restored :D
 

SRE

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OK... Lets start with the basics... Did you try the bulbs the other way around as the LED bulbs will only work one way and the 5W5 bulbs can be inserted either way.
 

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I think led bulbs are polarity sensitive. If yours are then you may have fitted them the wrong way round which would mean they did not illuminate.

I wonder if the Mercedes circuit detected the led circuit incorrectly corrected so isolated it until it was reset by switching the lighting circuit on and off, only a guess.
 

L John

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1. Can one test an LED bulb with a multimeter?

Just put 12V on it (as it's a 12V LED bulb), if the polarity it wrong it wont light up, if the polarity is correct it should light up.
Did you try it both ways in the holder?

A multimeter is not good because you would be testing it as a diode (an LED is a Light Emitting Diode) but the LED will have an in line resistor and could have a shunt resistor, so what readings would you expect to determine if its good?
A diode only lets current flow in one direction but the applied voltage typically needs to be at least 0.6V
A mulimeter without a diode test function might not give enough voltage on a resistance setting to allow forward flow to measure correctly.
Without the internal circuit of the bulb, any readings would be meaningless apart from maybe finding which is the anode but that can be found by connecting to a 12V supply anyway.
 
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Submariner1

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OK... Lets start with the basics... Did you try the bulbs the other way around as the LED bulbs will only work one way and the 5W5 bulbs can be inserted either way.

Yep I reversed them both, still did not light.
 
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Submariner1

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I think led bulbs are polarity sensitive. If yours are then you may have fitted them the wrong way round which would mean they did not illuminate.

I wonder if the Mercedes circuit detected the led circuit incorrectly corrected so isolated it until it was reset by switching the lighting circuit on and off, only a guess.

Thanks
Thats what I assumed.
 
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Submariner1

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Just put 12V on it (as it's a 12V LED bulb), if the polarity it wrong it wont light up, if the polarity is correct it should light up.
Did you try it both ways in the holder?

A multimeter is not good because you would be testing it as a diode (an LED is a Light Emitting Diode) but the LED will have an in line resistor and could have a shunt resistor, so what readings would you expect to determine if its good?
A diode only lets current flow in one direction but the applied voltage typically needs to be at least 0.6V
A mulimeter without a diode test function might not give enough voltage on a resistance setting to allow forward flow to measure correctly.
Without the internal circuit of the bulb, any readings would be meaningless apart from maybe finding which is the anode but that can be found by connecting to a 12V supply anyway.

Thanks
Yes I assumed being a diode it would only let current flow one way.
So I reversed the bulb by rotating it 180 deg. And still did not light.

My meter the fluke has a capacitor tesring facility but I thought that would not do.
My other meter does have a diode checking facility so might work if I knew how to use it. ;)

The packet does show an unlit bulb, and next to it a pic of the bulb rotated and a lit bulb.
So I felt confident I had tried all the possible ways.

My deduction was I got a pack with 2 faulty bulbs.

Assuming they should work in the MB?

My guess is I am unlucky to have 2 broken ones??
 
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Submariner1

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Just realised the Alarm guy left the 12V Yuasa batterys when he did the annual inspection.
Must try that tomorrow.
Will try them both ways i.e reversed.

I will be really stumped if they work.

As I cant think of any reason why they should not work in the CL’s boot
Unless there is something clever in the timer device, i.e if you leave the boot open for long, after a while the lights go off, could the LED be triggering that to shut down the bulbs?
 

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I got a set of osram ones for the focus sidelights

they put all the light in the wrong direction (thus reflected nothing) so were much dimmer than the std bulb's illumination and both dead inside 3 weeks

you could put resistors in to the circuit to pull something close to the correct current and see if the car wants to play ball

as EmilysDad says "CANbus electrickery"
 

M80

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LED's are polarity sensitive, as said they are diodes.
But recently I've come across some that must have a bridge rectifier in circuit, 4 diodes to rectify AC to DC, and rmove the reverse polarity issue.

Sub on yours I'm guessing that the design is to remove the 12V supply when it believes there to be a fault. In your case not enough load. I've seen it on number plate lights. A nuisance when doing as you wish. A loading resistor or canbus lamps would resolve that I guess.

At least now you know.
 
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Submariner1

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LED's are polarity sensitive, as said they are diodes.
But recently I've come across some that must have a bridge rectifier in circuit, 4 diodes to rectify AC to DC, and rmove the reverse polarity issue.

I had hoped as Osrams version is so much more £s, they would have addressed that. But I see your point.
Its not terribly important, more a question of knowing are both bulbs faulty or fakes.
Yes I know ... ‘always buy from a proper source’ ;). But as they said they were official partners and both were £8.99 delivered. Seemed a reasonable punt to buy them, 3 minute job and a nice bright boot area. Plus less drain when the boot is open.
Its not really worth the effort of fiddling with resistors etc.
I fundamentally dont like non-stock cars, but just swapping for Osram bulbs was about as far as I would drift from the norm.


Sub on yours I'm guessing that the design is to remove the 12V supply when it believes there to be a fault. In your case not enough load.

Yes, this sounds like a totally plausible explanation ... makes sense as I do have the very complex “intelligent Lighting system with Bi-xenon Lights, code 621”. So even more chance its been made complicated.

I've seen it on number plate lights. A nuisance when doing as you wish. A loading resistor or canbus lamps would resolve that I guess.

Shame, as I am pretty sure this will also screw up my plan to upgrade the under door puddle lights, so they matched the existing LED puddle lamps in the wing mirrors. :(

At least now you know.

Absolutely; however its irritating how all these really simple, basic things can catch you out.
Just looked on Amazon, that gives an automatic pop-up, saying “these bulbs are compatible with your CL500”. Oh Yeah!

When it stops raining, I will dig out the Yuasa alarm battery, just to see if they light up. If they do, then I will give up on the idea.


My other plan was to tap into the reversing lights (for the reversing relay/trigger 1mA drain) and add the Phillips LED DRLs, that I already have on the front; As an additional set of Reversing lights.
But with this experience, I could well imagine this issue might raise its head again. So will abort on that idea too!

Plus the wiring is over complicated by ‘Adaptive Brake Lighting’, (if you slam on the brakes and come to a stop, at speed, it will blink furiously, then automatically turn on the hazards for 20 seconds ... wow!) I bet any additional resistive load could give that an epileptic fit. (Being fair one shouldnt mess with complex electrics, without understanding the the circuit diagram).

Not to mention getting at the bulbs looks like you have to remove the whole rear light pod and the boot liner!
Designed by a Cretin!, there is oodles of space to access each bulb individually. Hey they could even have cut an inspection hatch in the boot lining. Whoa that would make it service friendly!
But then imo the lighting designers at Mercedes are mentally retarded ... so to be expected!
 

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If it is your intention to play with various alternative (LED, SMD, COB, et al) light bulbs (and you'll go through a good few, before you find ones that work reliably-ish), you might want to invest in a switchable power supply with an automotive socket, so you can bench-test your stuff.

Avoid the cheapest ones - I bought Coleman Campingaz Euro Transformer from Amazon, over seven years ago, and it's been excellent. (ref: 203442, model JT-DC12V5A(II) - it handles up to 60W, as you can see from the model code.
 

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Reversing lights are not linked to adaptive brake light circuitry.

Adding (within a reason) LEDs to existing tungsten bulb will not require additional load resistors.
 
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Submariner1

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:eek: you'll upset Craig .... :shock:

Why should it? , when I once said he only defended their lunatic designs, because his living depended on contracts with Mfgs. (which I was pretty sure, I had seen in an earlier post]
He emphatically said he did not contract for Mfgs.

Hes a smart guy maybe he can get them to look at the basics.
Only by them self critiquing will things improve ... or customers bitching!

I think the post 2015 cars have radically improved in illuminating the road adequately.
 
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Submariner1

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Reversing lights are not linked to adaptive brake light circuitry.

Adding (within a reason) LEDs to existing tungsten bulb will not require additional load resistors.


I would agree reversing lights are unlikely to be linked to Adaptive Brakes ... what I meant was I suspect having ILS and Adaptive Braking lights means its likely the whole lighting system is quite advanced i.e. its not a simple on off switch delivering enough amps to light a 5W bulb.
OK it might not throw the usual Canbus broken bulb messgae, but it sure is doing other things, not normally associated with a simple boot light!
 

Botus

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canbus can be useful.... where aftermarket boys use its capability the right way (this is a toy for BM motorbikes)

http://hexezcan.com/

ezCAN_v1707.7_main_window.png
 
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Submariner1

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LED's are polarity sensitive, as said they are diodes.
But recently I've come across some that must have a bridge rectifier in circuit, 4 diodes to rectify AC to DC, and rmove the reverse polarity issue.

Sub on yours I'm guessing that the design is to remove the 12V supply when it believes there to be a fault. In your case not enough load. I've seen it on number plate lights. A nuisance when doing as you wish. A loading resistor or canbus lamps would resolve that I guess.

At least now you know.

Just a thought, if its shutting down because the load is too small.

A
- would one of these cheap Canbus Friendly bulbs work? Because I assume they put in a resistance to fake the 5W bulbs resistance.
I= 5/12 .. 0.416A
I= V/R , .. 0.416 = 12/R
R= V/I .... R = 12/0.416 ...= 28.8Ohms
Or is it not that simple.

B
- if it is ... would that resistive load in the Canbus friendly bulb get as hot as the normal 5W5 wedge?
One of my other goals, aside reduced current drain is ideally to reduce heat.
Or as a minimum not exceed 95% if the normally existing heat with std. bulbs.
 

L John

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LED's run cooler than filament bulbs because they're more efficient (I know you are aware of that).
Increase the current to the same level by using a shunt resistor and the same amount of heat will be dissipated.
The shunt resistor can be away from the bulb so the heat can be dissipated elsewhere.

Basically, amps causes heat though that statement is not entirely true.
e.g. pylons run at very high voltage to reduce the amps, if they ran at 240V and transferred the same amount of power (watts) from the power station, they would melt due to the huge amps.
Fuses blow because of amps (the fuse melts from heat).
 
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