Ambient Lighting ** WITH PICTURES***

Discussion in 'Electronics' started by mbenz1, Apr 5, 2014.

  1. mbenz1

    mbenz1 Hardcore MB Enthusiast

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    Hi Guys


    This is my second try of getting some help on a Ambient lighting problem in my dad's W221 2008 S320.

    As you can see in the pictures, the LED strips are bright at some parts and very dim (like dots) at other parts.

    The main LED lighting across the centre console is bright near the end but gets dimmer near the middle of the centre cabin.

    I have checked the fuses in the engine compartment and both fuse boxes at the front left and right doors but all seem to be fine.

    I assume both batteries in the car are okay, since there are no warning lights and the car cranks okay and all the electronic features work okay. With just the ignition on, I turned on the headlights with full beam and then turned them off but noticed no change in the brightness of the Ambient lighting....

    Guys, any ideas on what the problem can be? Its very rear for LED bulbs to fuse also...I have also tried the command Ambient lighting settings but no joy.

    Would it be an easy job to replace the LED strips and removing the wood, if they were to be faulty?

    Thanks.
     
    Last edited: Jun 13, 2016
  2. Dieselman

    Dieselman Banned

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    I would guess that the power is fed from one end and there are resistors along the track. They go dim due to the feed voltage being low.
     
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  3. OP
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    mbenz1

    mbenz1 Hardcore MB Enthusiast

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    Okay. Any suggestions for a low feed voltage? Would it be due to the battery not giving enough input power or could it be due to a bad joint somewhere in the circuit?

    Would you know if its possible to get a circuit diagram for this lighting system from somewhere?

    Also, am I correct in saying that the LED bulbs in the strips are not fused because if they were, the LEDs will not light up at all?

    Thanks for your reply.
     
  4. whitenemesis

    whitenemesis MB Club Veteran

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    What effect does adjusting the brightness setting in the cluster menu have?
     
  5. OP
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    mbenz1

    mbenz1 Hardcore MB Enthusiast

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    Its basically the brightness level. It ranges from 0 (off) to 5 (fully bright) and there are no other settings.

    The LEDs that are not fully functioning do get dimmer or brighter if the brightness is changed through the Comand setting, but their light output is much lower (as seen in the pictures).

    When I took the above pictures, the brightness was set to full (5).
     
  6. OP
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    mbenz1

    mbenz1 Hardcore MB Enthusiast

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    Both batteries have been changed either in the last service or the service before the last. Genuine MB batteries fitted by MB.

    I'm totally depleted of ideas regarding this problem...
     
  7. c63chris

    c63chris Hardcore MB Enthusiast

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    As has already been said it looks like a voltage issue in which case I would be checking how the units are connected and making sure the connections are sound. Low volts can be caused by a loose connection but it can be a swine to find. Start at the LEDs, make sure the connections are tight and measure the volts at the LED. If the volts are fine then it's new units time.
     
  8. OP
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    mbenz1

    mbenz1 Hardcore MB Enthusiast

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    I would have absolutely no idea how to check the connections, since I am assuming that the LED strips will ne to be taken out, in order to check each connection. They are embedded under the wood...

    It looks like a Mercedes specialists job, unless I could find a complete circuit diagram of the Ambient Lighting system and the instruction to remove the strips

    I know MB parts/service department will not give any instructions on how to remve the strips etc... but would they be able to provide me with a circuit or components diagram of this system??

    Thanks.
     
  9. Diesel Benz

    Diesel Benz Hardcore MB Enthusiast

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    The wiring diagram is absolutely simple. I cannot see how it would be a voltage feed issue, more likely an internal failure of components/wiring within the strip panel.

    You will have to find instructions to remove the trim strip and measure the components there.
     

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  10. OP
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    mbenz1

    mbenz1 Hardcore MB Enthusiast

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    Much appreciated for this diagram and information you have provided. My dad has a close friend, who is an electrician and programmer, hopefully he will be able to measure the components and find out what the problem is.
     
  11. DennisTheMenace

    DennisTheMenace Member

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    I expect you will find that its an LED at the "bright end" and the rest is an internally ribbed fibre optic "light guide" in the dark the light output looks fine. The led's you say look dim are in fact the ribs in the optic light guide.

    Fibre optics are being used more and more in cars for things like tail lights (Mondeo,bmw range, scenic, etc etc) to make them stand out, as you can route it in all manner of ways.
     
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    mbenz1

    mbenz1 Hardcore MB Enthusiast

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    This thought also came in my mind. Lets say for the time being that its an fibre optic LED system, there is still definately a fault in the system. The pictures that were advertised by the seller included one where the lighting was on. In that picture, the ambient lights were fully bright all around - no dim points anywhere.

    If there is an LED at the start of the strip, what could be causing this problem? Could it be a blockage in the fibre optic guide or could the fibre optic guide be damaged?

    I have also seen the official MB W221 Ambient lighting interior pictures and the light output is the same accross the entire span of the strips.

    What do you mean by the ribbs?

    I am pretty convinced that it is an electrical fault in the system, since more than one strip is not giving the correct light output
     
  13. DennisTheMenace

    DennisTheMenace Member

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    I very much doubt there is an issue with the fibre optic light guide, the photo in his advert could have been done with a decent camera and a delay would make the strip appear brighter.

    If its just the one door that's faulty just have a check that there is not an LED at the other end, but usually these systems just have the one LED as it is sufficient.
     
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  14. ScottHarry

    ScottHarry New Member

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    Looking at picture 2 the light output is diminishing from left to right of the strip by one LED at a time. That would indicate that a possible volt drop is occurring across each proceeding LED feeding the next? So a diminishing effect is happening. The diminishing is a big clue to the fault.

    If the LED's are connected in series LED Wiring In Series Tutorial this diminishing effect would occur I believe. But to drive that amount of LED's in series the voltage applied would need to be rather high to overcome the the voltdrop of each LED in the chain/array http://en.wikipedia.org/wiki/LED_circuit#LED_arrays.

    Possible conclusion that the special high voltage LED driver power supply for those strips in that door (where special voltage = maybe 3V x amount of LED's + some more) has a reduced voltage output? So nothing to do with the cars two batteries. There is a possible DC to DC convertor maybe taking 12V in and up'ing it to a much higher value out. This would drive the LED's and have some form of current limiting built-in.

    I believe anything over 40VDC ish is considered dangerous so it will probably be lower than that. Telephone lines use 50-60VDC for example but >70VAC when ringing to drive a remote bell back in the day but still are like this today.

    So find out what the voltage feed should be in volts and where the DC to DC power supply is or if it has a separate current limiter stage/circuit- probably not a simple resistor in a MB. Will probably be a semiconductor/IC current limiter and check those :thumb:

    Hope that helps
     
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  15. ScottHarry

    ScottHarry New Member

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    Been thinking - in picture 2 there are about 20 LED's in the chain. If they are special low volt drop SMD LED's of say 0.5V each at full brightness, the volt drop over the 20 would be 0.5V x 20 LED's = 10V. If this is the longest chain of LED's then 12V would be enough.

    The schematic diagram someone posted shows a transistor symbol within the top module feeding the lower LED modules. The top module may contain current limiting circuits and or constant current circuits. The latter is used to raise or lower the voltage (within limits) until the desired/programmed amount of current is flowing in the circuit. This would have 5 step values of current switch-able by the Ambient Light user control. So maybe the top PCB/board is faulty? Also try opening/slamming the door while watching the lights also move and wiring harnesses and tap around while watching the lights may show something - should there be a dry joint on the soldering of a component or a loose wire/connection.
     
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  16. OP
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    mbenz1

    mbenz1 Hardcore MB Enthusiast

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    ScottHarry, firstly please accept my apologies for not replying to your above quotes...I was just browsing through my old threads today and noticed you had replied to this thread.

    Secondly, many thanks for your useful and handy comments above. I also think that the LEDs have a low voltage drop of say 0.5 V per LED so maybe there is no current limiting stage/circuit...

    I have got hold of the WIS sheets for removing the ambient lighting strips (sincere thanks to DieselBenz) and need to take out some time to remove atleast one strip and check the harness and connections and voktage readings etc...but looking at the WIS sheets, they mention the use of correct torque settings for the panel screws etc and I need to get hold of a torqe screwdriver for that :(. I will keep this thread updated if I get anywhere with sorting this problem out.
     
  17. Emre81

    Emre81 New Member

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    Did you fix the problem i have the same problem her need help pls
     
  18. OP
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    mbenz1

    mbenz1 Hardcore MB Enthusiast

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    Unfortunately not yet. Just came back to UK yesterday. apparently to undo the screws etc on the panels, a torque screw driver is needed and also special.adhesives are needed for the bolts and screws etc... Will be considering getting the job done by either MB specialist or MB...
     
  19. raz2050

    raz2050 New Member

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    Mine looked the same, replaced the whole trim, still is the same. I don't think there are mini LEDs all around. Still trying to figure it out. Is it suppose to be a same brightness all around?
     
  20. OP
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    mbenz1

    mbenz1 Hardcore MB Enthusiast

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    Did you replace the whole light strip and still the problem is there? Its definitely supposed to be the same brightness all around... I have a W221 pre-facelift brochure with a picture of ambient lighting and its bright everywhere. Considering your investigation, I'm thinking the problem has to be in the electronic module(s) that supply the power to the strips...

    Which strip did you replace and howmuch did the parts cost? From where did you get it replaced?

    Do you still have the old strip with you by anychance? If you do, its worth a shot to open it up and see if you can find any loose connection or burnt joints etc...I think there are also resistors between the LEDS...
     

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