LEDs as Instrument/dash lights in 123 series - PeachParts Mercedes-Benz Forum

Gil · #1 10-11-2007, 09:02 PM

Ok, we all hate the dim bulbs of the 123 dashboard and climate control lights, but there isn't much we can do about it other than clean the housings or try higher wattage bulbs (which tend to melt the housings). Someone suggested on another post that LEDs (plain white or colored) would work well for this application.

Something like what's available here:

http://www.jamstrait.com/snakelights.htm

I went out to Autozone and got a set (different manufacturer, but same basic thing). The LEDs require a 12v power supply, which isn't provided by the stock wires going to the CCU, etc. I guess it'll take some rigging to a switchable 12v supply from the fusebox, preferably one that's linked to the headlights.

This seems like a workable solution. Anyone ever try this before?

funola · #2 10-11-2007, 09:08 PM

Unless each LED has a built in current limiting resistor, you will need to add one otherwise it will burn out. Let us know how it works.

Gil · #3 10-11-2007, 09:10 PM

Quote:

Originally Posted by funola

Unless each LED has a built in current limiting resistor, you will need to add one otherwise it will burn out. Let us know how it works.

The ones I picked up were cheapos, 4 per pack for around 8 bucks. They're just LEDs at the end of two wires, that's it. I don't think there are any current limiting sensors. Are you suggesting a direct line to the battery will burn them out instantly? That wasn't what I had in mind.

Would this still be a problem hooking up to a fuse box sourced supply?

funola · #4 10-11-2007, 09:49 PM

Unsolder one of the LEDs, wire it up to the car battery and if it does not burn out you're golden.

dwoloz · #5 10-11-2007, 09:52 PM

Quote:

Originally Posted by funola

Unless each LED has a built in current limiting resistor, you will need to add one otherwise it will burn out. Let us know how it works.

What the OP is describing sounds like a boxed kit that is basically plug and play. No LED that I know is 12v, this kit already has the circuity to run them on 12v.

techguy512 · #6 10-11-2007, 10:00 PM

These guys have a large selection of both LED and incandescent bulbs for automotive (12V) applications.

http://autolumination.com/index.html

I've ordered from them. Quite reliable.

Chad300tdt · #7 10-11-2007, 10:08 PM

Check out the info in this thread. I ordered from LEDlights.com and am very happy. I tried other bulbs and finally am happy with the results. The instrument cluster is so much brighter it looks like a newer cluster.

http://www.peachparts.com/shopforum/showthread.php?t=200431

Gil · #8 10-11-2007, 10:26 PM

Quote:

Originally Posted by Chad300tdt

Check out the info in this thread. I ordered from LEDlights.com and am very happy. I tried other bulbs and finally am happy with the results. The instrument cluster is so much brighter it looks like a newer cluster.

http://www.peachparts.com/shopforum/showthread.php?t=200431

Cool - which bulb model # is the one that fits into the CCU sockets? They weren't talking about 123s on that post, from what I saw.

eyeguy · #9 10-11-2007, 10:26 PM

Do LEDS work with the dash light dimmer? Do they get brighter as you turn up the rheostat, or do they just have on and off?

funola · #10 10-11-2007, 10:29 PM

Quote:

Originally Posted by Chad300tdt

Check out the info in this thread. I ordered from LEDlights.com and am very happy. I tried other bulbs and finally am happy with the results. The instrument cluster is so much brighter it looks like a newer cluster.

http://www.peachparts.com/shopforum/showthread.php?t=200431

Is this what you bought?

http://www.ledlight.com/SearchResult.aspx?KeyWords=45689

Aren't there 3 bulbs (one for each gauge) in the cluster? Do these plug right in?

Shawn D. · #11 10-11-2007, 10:52 PM

Quote:

Originally Posted by eyeguy

Do LEDS work with the dash light dimmer? Do they get brighter as you turn up the rheostat, or do they just have on and off?

Yes, the intensity of LEDs will vary with voltage, but will likely not match the voltage/intensity curve of the incandescents. Also, at a certain low voltage (depending on the LED, resistor value, and supply voltage), the LED will simply go off instead of continuing to taper down.

Chad300tdt · #12 10-12-2007, 12:08 AM

To answer the questions, Yes this is the bulb I ordered: 194 super flux bulb #45689. There are two bulbs in the cluster. They are in twist-in sockets located in the top back of the cluster. These LED bulbs fit the socket with no problem. The LED head fits into the light tunnel snugly but easily. The side firing and top firing LEDs utilize the reflective tunnels very well. The LED bulbs are polarized so they need to be inserted the correct way into the socket. I got one right the first time and the second I had to turn around. They made the dash bright enough to see and read every gauge including the trip meter at the bottom in the dark. I also ordered the dome light LED replacement and it makes a huge difference also. These bulbs draw less power, produce far less heat and last a very long time. They are worth the price and there is nothing to do but plug them in and enjoy seeing the way it should have been from the factory.

patbob · #13 10-12-2007, 12:15 AM

Quote:

Originally Posted by Gil

Cool - which bulb model # is the one that fits into the CCU sockets? They weren't talking about 123s on that post, from what I saw.

Don't know about that place, but I believe they are a standard 74-w mini wedge base bulb. BTW, CCU wants the ones for illuminating the buttons to be side-emitting. I got one that emits out the end and it didn't light the buttons too well. Dandy on the temp wheel tho.

The dash dimmer won't dim the LEDs perceptibly -- it's a very small variable resistance in series with a very large current limiting resistor. Some places sell a large ballast resistor you can hook inseries to drag the voltage down, but you won't be able to mix-n-match bulb types. You'd need to rig a variable voltage source to the dimmer resistor to dim both kinds in mixtures.

Gil · #14 10-12-2007, 12:16 AM

Quote:

Originally Posted by Chad300tdt

To answer the questions, Yes this is the bulb I ordered: 194 super flux bulb #45689. There are two bulbs in the cluster. They are in twist-in sockets located in the top back of the cluster. These LED bulbs fit the socket with no problem. The LED head fits into the light tunnel snugly but easily. The side firing and top firing LEDs utilize the reflective tunnels very well. The LED bulbs are polarized so they need to be inserted the correct way into the socket. I got one right the first time and the second I had to turn around. They made the dash bright enough to see and read every gauge including the trip meter at the bottom in the dark. I also ordered the dome light LED replacement and it makes a huge difference also. These bulbs draw less power, produce far less heat and last a very long time. They are worth the price and there is nothing to do but plug them in and enjoy seeing the way it should have been from the factory.

What about the itty bitty ones in the CCU panel, where the fan switches are? Did you put an LEDs in there also?

- ok, thx - just got your last post!

Chad300tdt · #15 10-12-2007, 12:23 AM

I tried the 74 Wedge base LEDs in the CCU and wasn't impressed. I think the standard bulbs are better suited for that application. The LEDs ended up looking half as bright as the standard bulbs.

I haven't tried to dim the LED in the cluster, but if it doesn't dim who cares? The reason I want LEDs is so I can have my dash as bright as possible. There is never an occasion where I would want them dimmer.