Help With Dash Lights Please... - PeachParts Mercedes-Benz Forum

structure · #1 02-05-2004, 02:24 PM

I was wondering how to remove the dash lights(where the rear light switch, a/c knob, and rear defroster switch is. The lights for the rear light switch,a/c knob, and rear defroster do not light up and I wanted to fix them.(DO THEY EVEN LIGHT UP?) If anyone knows how to replace the bulbs so they work please help. The rear defroster button only lights up when I turn it on when it's off it does not light up but on my 1977 300D the button lights up even when off. (I put brand new fuses in so I know it can't be a fuse)

Here's some pics. to see what I am talking about:

Rick Miley · #2 02-05-2004, 03:26 PM

Let's start with the A/C knob, circled in the second pic. It pulls straight off. The bulb is then visible. But don't replace it yet.

When you get the knob off, you'll see the big brass nut underneath. Remove that. Carefully pry out all of the accessory switches in that upper panel. When you do, you'll find that each has a fiberoptic cable in addition to the the wiring.

With all the switches out, you can now remove that whole panel. Pry very carefully because it is easy to crack. Once out, you'll see the bulb that attaches to the back side of it.

The heater control panel has a similar arrangement, with two bulbs mounted on the back and one in the middle of each knob. Be sure to get the right size bulbs for these, as it's easy to make a mistake and get the next brighter ones which will be too hot.

Now for the fiber-optic lighted switches, you have to replace the bulb at the center of the "octopus." Follow those lines until you find it down inside the dash. I found that easiest to do when the radio was removed.

structure · #3 02-06-2004, 12:50 AM

Well, I have replaced the lights on the lower dash(heater knobs,fan knob,etc.) w/ the bright bulbs and to the tell you the truth I like them. That's how the dash should be lighted up. I'm fine with them(even though they do get hotter). I've taken out the switch covers to see there are 2 bolts holding down the A/C control. Now does, the A/C knob just pull right off. Because it does come up but I know that's just to turn the A/C compressor on. Should I just pull it off harder to get the knob off? I know in order to get to the bulbs for the A/C control(backlight) I have to take loosen the 2 bolts holding it in. I will try to get pictures to show you.

BTW, THANKS SO MUCH!

whunter · #4 02-06-2004, 07:43 AM

Hello structure
When Rick Miley says too hot; he means they can melt things.
Have a great day.

Rick Miley · #5 02-06-2004, 09:02 AM

Actually, I have the hotter bulbs in the heater control panel because the previous owner put them there. They haven't melted anything yet, but then I hardly ever drive that car at night. But those knobs get so hot to the touch that I think those bulbs cannot be good for the long term health of the plastic. It is well known that brighter (hotter) bulbs in the instrument cluster will melt the housings.

There are at least three different versions of those panels that I have seen, so an exact replacement may not be easy to come by. So I would prefer to err on the safe side and get cooler bulbs.

Anyway, yes the A/C control knob just pulls straight off. Pull harder. Under the knob you will find the big brass nut that must be removed. Then you can pull the panel.

mccauleybil · #6 11-09-2011, 09:35 AM

Just in case anyone else is replacing their bulbs...

My 1982 300SD, with an electronic instrument panel uses:
Small Bulb - Sylvania Osram 2721MFX 12v - 1.2w (Napa PN 17035 at $2.00 ea)
Big Bulb - Sylvania 2721LL ($2.00 ea)