I recently purchased some LED bulbs from SuperbrightLED.com, for my instrument lights.

AMAZING lights, however, I discovered that due to differences in the amount of resistance, LED bulbs (unless load resisted) cannot be used in the Anmeter warning light, or the brake pad wear indicator sockets... When I had an LED in the battery light socket, when the car was started, the brake and battery lights were on. I thought this was just a cossed connection somewhere, as the LEDS are +/- spacific.
Not true, when the battery light is on the circuit is broken and even though the car is running, that LED is somehow interrrupting the charging circuit. Replaced it with a standard 194 bulb, everything works fine.
When I had an LED bulb in the brake pad socket, when the car was started the light would light up as ususal, and go out, but when I put on my seatbelt the seatbelt light and the glowplug lights would light up.

The moral of the story. LED bulbs (72 and 194) work excellently in the instrument illumination sockets, and really spectacularly in the turn signals and high beam indicators and glow plug sockets. None the less I give two thumbs up for superbrightled.com.

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RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

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FACEBOOK: PANZER450

I will also post some photos tomorrow when I have a chance.....

__________________
RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

____________________________
FACEBOOK: PANZER450

For the reasons that you have discovered, many LED installations need a "ballast resistor", which is not in series with the bulb but is in parallel with it, in order to consume the same amount of current as an incandescent bulb would. I had to make my own ballast when I replaced the 3rd brake light bulb with a home made LED panel; otherwise, my "bulb warning" light would come on in the dash.

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86 560SL
With homebrew first gear start!
85 380SL
Daily Driver Project

http://juliepalooza.8m.com/sl/mercedes.htm

I don't see a link for auto bulbs on their site. Can you post one?

On a related note, I used to have Raybrig "hyperwhite" 194 wedge bulbs in the instrument cluster. At first they were very effective, however over time I noticed decreased illumination.

I pulled the cluster last weekend and discovered that the Raybrigs had melted and discolored the ends of the plastic "prism" that channels light from the bulbs to the front of the cluster.

As a result, LEDs seem to be the best way of increasing illumination without a substantial risk of damage to the plastic parts of the cluster.

LED's do produce heat, but not nearly as much as an incandescent bulb.

Melting the plastic means that substandard materials were used in its construction. A different brand may help.

are they dim-able....is that a word?

LED's can be dimmed as varying the input current will vary the light output. However, their current requirements are much lower than incandescent bulbs, so a dimmer made for incandescent bulbs won't work very well with the LED.

With proper shunt and series resistors, the LED could pretty closely mimic the incandescent bulb and work with its dimmer.

heh, I know, I guess what I meant was if I went with these "plug and play" LED's for say the main cluster lights, will they dim as I rotate the dimmer switch?

I haven't checked any, but find it doubtful if you replace them all. If you leave enough incandescents in there, they may dim just fine.

Raybrigs are incandecent.