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Dome light upgrade & heat reduction

7K views 11 replies 5 participants last post by  LeftCoastGeek 
#1 ·
This is applicable to all W124s. As most of you know, the dome light gets really hot if it stays on for any significant of time.

I've found a solution that kills 2 birds with one stone. The standard bulb is a 10W and due to the constrained space is the main culprit for the heat issue.

OSRAM has a LED replacement unit (see link) that is virtually plug & play and only consumes 10% (1W) and is brighter. Due to very low power consumption, there is zero heat and the chance of the battery getting drained overnight is virtually eliminated.

There are only a couple of things to consider when installing it. 1) The copper prongs need to be pushed in a bit as the LED bulb if physically shorter than the incandescent one. 2) The access door to the bulbs needs to be left ajar. IF the door is fully closed it will cause the bulb to fall out due to the shorter size of the LED bulb. However, leaving the access door ajar does not cause any squeaking or rattles so all is good.



I'm very pleased with it and plan to do the rear dome light as well and plan to see if it will work with the license plate lights as well although I suspect the bulb out monitoring module is not going to play nice.

I will let the pictures do the talking. On a sidenote, I also replaced the amber turn signal bulbs with OSRAM DIADEM chromed bulbs. I think it came out rather good.

 

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#3 ·
#4 ·
I replaced my dome light with LED quite awhile back. I don't remember what type it is, but it was the correct fit. I think it was built more like the kind Volvo shows, but not as wide, IIRC. I'll have to look later. It works great though. I also replaced the one in the back seat.

My only issue is that I have not been able to find an LED replacement for the map light bulb. I bought several that fit the socket, but none of them actually light up. I'm guessing it might be a polarity issue and I just need to reverse the wires at the bulb socket, but I have not tried that yet.

I used some for my license plate lights that are like the Osrams you got.
 
#5 ·
I did a few LED conversions on different cars. I found that hardwiring works best. Even fixing the contacts with a little solder avoids flickering and loose bulbs. That's why I don't like the capsuled bulbs a la OSRAM. The open units with CREE style SMD LED modules are brighter. Only exception for me would be if you really want to keep the reflector and the LED invisible, like on classic cars or because it's a really good and spot reflector. Volvo745 is right: If you aim them right the light output is much better. They are cheaper too. Just be careful to match the color otherwise it looks weird. I prefer warm white in older cars. If you like your light more diffused you can fabricate a filter out of old milk- or water containers. This is just for interior lights. For exterior lights I prefer to search for the perfect sized bulb to utilize the reflector. But I also try to keep things in place here as good as possible.

Here are a few examples of what I did on the W124. I don't have a photo of the front dome light, but I removed the reflectors and 3M-taped the light modules to the cover.

Rear dome light: Smooth sanded and clear coated with the mentioned water container plastic diffusor inlay.




Puddle lights (the brighter, the better):


Tail light:

Plates:

Center stop:


I don't post all of it. I guess you get the picture.
 
#8 ·
Any issue with the bulb out warning light coming after installation of the LEDs in the license plate, tail light???

Also is your cruise still fully operational?
No warning light but my guess is it's not working since it doesn't light up when starting. Cruise control never worked since I bought the car. Haven't killed all the little bugs yet. So why bother with LEDs before fixing other issues first? Well, at first it's an over twenty year old car. Even without being baked under the California sun most plastics get brittle over the time. Some parts just wouldn't survive another disassemble. Best example is the center stop light. That thing felt into pieces when I tried to open it. I glued it all back together, even painted it after I was done. But of course there is no way to open it anymore. Also LEDs won't get that hot like the classic bulb which is also an issue with older plastic parts (speaking about warping tail light bulb holders). As for the interior lights: I want it bright. Not stupid space ship bright but enough light to find things when it's dark outside. If something works with bulbs I usually don't touch it. But if I have to fix it anyway for some reason I usually mod it to LED.
I replace exterior lights for the same reasons. Some lights are so difficult to get to that I really don't want to do it again. Then they are brighter. I want my brake lights to explode through any smartphone of anybody texting behind me or driving a Toyota Corolla, Camry, Avalon, and bypassing the outer layers of the brain, making them to stop IMMEDIATELY because their central nerve system told them to.

I don't like the error free LED bulbs or resistor hacks. I get bad skin when I see a setup with a heat sink on top and of course it needs as much energy as it would if it were incandescent bulbs. The only way to stop hyper flashing and bulb errors is to modify the relay. On older cars that's easy to do. It usually involves soldering a resistor onto the circuit board. Any TV repair shop can do it for you (if you tell them what to do).

Is the cruise control related to the bulb warning?
 
#7 ·
indeed at least on the post-face-lift cars (I only looked at that wiring diagram), it looks like the license lights *are* on the bulb failure sensor. they sell LED lamps that are 'canbus compatible', these have sufficient current flow to usually fool those, but of course, that means they are no longer the uber-low power of a native LED lamp.
 
#9 · (Edited)
Cruise control is tied into the brake lights as it uses/senses the brake lights to cancel cruise when the brake pedal is activated.

If you use the wrong bulb type, cruise typically will not work. Ditto if one or more brake lights are burned out.
 
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