Hi, I have an 87 300SDL and although I have read quite a few posts about upgrading the instrument cluster lighting to LEDs, I still need help. I bought all the LEDs I need, I install them and they don't work. I insert the old incandescent bulb and it works. What am I missing? I know it's got to be something stupid. I also saw some cool self powered dials on a youtube video W126 SEC LED Dial Faces - YouTube . I wrote the guy who uploaded it and asked where he got them but he has not replied. And the last one, does anyone know about any after market clusters for the w126 that are more updated than the OEM culster? Thanks.

LED bulb may work by reversing. They have + and - contacts. There was a ebay seller making custom (plasma?) lighted dials.
The LED bulbs help a little.

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Present
1987 300SDL
1991 300SL
1990 560SEL
2001 ML320

Past
1969 200D 1979-82
1983 300SD 1984-85
1972 250C 1982-02
1995 S350 2011
1997 S320 2012

LEDs almost always need a resistor. The package they came in should specify the resistor.

NJ300SDL - I did turn them but no success.
liquiddog - No resistor. They are wedged end that fit just like the incandescent http://www.ebay.com/itm/200957863670?item=200957863670&viewitem=&sspagename=ADME:L:OC:US:3160&vxp=mtr. They are sold as "direct replacement", in other words, nothing else is needed . . . unless I AM supposed to do something else. Any other thoughts?

Sure way to figure it out. Hook the led up to enough batteries to make 12v. Or just the car battery. Just don't electrocute yourself. Does it light up?

If it lights up "manually" and you have proven there is power by getting the regular lights to work, it means you aren't making contact.

great suggestion. I will try that.

Just keep in mind what the other poster mentioned. LEDs can only be hooked up one way. It's a diode that glows. Hook it up the wrong way and it cooks like a fuse blowing.

I did some work for a forum member on here's son. The son had a thread about resorting his early model 190E. I cant remember his screen name at the moment though. In a few emails, we discussed improved lighting for the cluster.

Here is what he came up with on his late 124 300D.

Before



After



Using these:
194 LED Bulb - 1 SMD LED Wedge Base | Miniature Wedge Base LEDs | LED Car Bulbs | Super Bright LEDs

I believe he also might have swapped out the optics/light guides with that of a later model 124.

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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

Thanks for that link. I'm still trying to figure out how to pop the glass out gracefully. It may be a high heat/humidity thing in Texas, but the plastic inside all the clusters around here is extremely oxidized and gets sort of rough. I got the glass out of one of them and it is "acceptable" but I scratched up the black trim around the glass a little doing it. I have a second cluster and I'm eyeballing it and thinking maybe cutting the face off at a non-visible location is a better option, then using gorilla glue to put it back together.

Most single leds run on either 3.3 volts or 2.0 volts. If you plug them into 12vdc they are destroyed in about 1/10th of a second.

Red leds are 2.0VDC units while all others are 3.3v

A 500 ohm 1/8W resistor usually works good.

The glass can be gently pulled out. Under it you will find that the two leads
are soldered in place with a resistor. Snip the leads to fit and solder your led in. Makes no difference which side goes to the resistor.

Carefully to insure NO shorts, push the led into the housing. Insert housing into your cluster and try it. If it doesnt work, pull it out and reverse it.

The turn signals on my 123 can be seen verrrrry easily standing by the rear bumper.

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1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

Sorry if this is a dumb question but can you still use the dimmer is you change to LEDs? That after photo is very bright and perhaps too bright for some driving conditions?

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1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).

Yup, leds change brightness when voltage changes. They aren't on or off.

Thanks everyone for the input and specs.
James Dean - That is the kind of brightness I want to have. I have a spare W124 cluster around so I will look at the optics/light guides. I read that somebody replaced the prisms and covered the surface with stick aluminum foil for a great gain in luminosity. I noticed on the link for the LEDs you used that these are a direct 12V replacement, no resistors needed, correct?

No resistors needed. Direct replacement.
I'm not familiar with the W126 cluster, but the W124 cluster pictured has the late model light guides transplanted into an early model cluster.
There's also some plastic around the two bulbs that needs to be cut out to resemble the improvements made on the late model cluster.

If I remember correctly, the bulbs used were the cool white option. Several other colors are available.

You're right, they are too bright unless you dim it a little.