Hi All,

So I was driving this evening (just about 15 minutes ago) and I lost some of my interior lights. Specifically, here's what I lost:

1) The instrument cluster lighting (both bulbs)
2) The lighting that lights the ACC buttons
3) Lights that light all my console switches (windows, sunroof, etc).

Here's what still works:

1) Front dome light and reading light
2) Sunvisor vanity mirror lights
3) Rear dome light
4) The hazard switch flashes correctly
5) Gear selector numerals still illuminate
6) Turn signal indicators still illuminate

It all happened suddenly, and all without any warning.

I've checked my fuses and while none are blown, I do have quite a few that seem pretty marginal. There were all the fuses in the fuse box (not sure if there are other ones hiding somewhere?)

As a note: I have been disassembling and reassembling the power window console switches some weeks ago. When I put the passenger side switch block back in, I noticed they didn't work and didn't illuminate. I figured I'd just live with it until I had some time to take it apart again. Could I have caused some kind of a short? Seems unlikely.

Barring any more advice, my next plan is to get myself a replacement set of copper fuses (my current fuses are aluminum and certainly look fairly old). Then we'll see what happens. Everything /works/ fine, but it's annoying having no interior lights like that. Were I a betting man I would feel like 95% it must be a fuse, but after reading the fusebox lid, I feel I am no closer to guessing which particular fuse might be the culprit.

Any ideas?

Thanks in advance! You guys are a great help!

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1984 300D Turbo, 326000 Km, Thistle Green Metallic

It sounds like its the dash rheostat. You can turn it and it turns the brightness up and down. Sometimes it fails, leaving you in the dark. Try playing with it and it may come back online, otherwise youll have to replace it or jumper it.

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1981 300SD 512k OM603

I thought about this too - and I spent some time looking around for the rheostat but (and maybe I am just slow of mind lately) I was totally unable to find it. Where the heck is it?

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1984 300D Turbo, 326000 Km, Thistle Green Metallic

It's the knob on the left in the instrument cluster. Try turning it a few times and see if the lights come back on. If not pull the cluster out and the rheostat is on the back of the temp/fuel/oil gauge. It in the lower right corner if you are looking at the back of the gauge.

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Hmmm! So my cluster has two 'knobs' - the one of the left resets my trip odometer if I push it in (but you're saying this knob also twists for the rheostat?) and the knob on the right, to set the clock.

I'll be out for a drive later today so I'll give the thing a twist and see what happens! Hopefully it's that easy.

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1984 300D Turbo, 326000 Km, Thistle Green Metallic

You got it.

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Hah! So I feel like a bit of a fool but yes - fixing this was not really a fix at all - just twiddled with the dash rheostat and all was fine. Thanks! I never knew where the rheostat was, until now!

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1984 300D Turbo, 326000 Km, Thistle Green Metallic

You can leave the control full on if you like. There have been no reports of induced blindness resulting.
Mercedes was an originator in auto features and terminology. I think they were the first to coin the term dark side in describing their electrical design of the cluster.
I still wonder what they were thinking when they designed the dash illumination. Worse yet on a car that prides itself on running production changes. It remained the same since introduction of production of that model over the years.
Thirty grand back then and you want to see the instruments at night as well? Perhaps it was just a common conspiracy. If you cannot see a slipping odometer it does not become a warranty issue as well crossed my mind. Or perhaps just an additional safety feature. What you cannot see again cannot hurt you.
Maybe they did not just want to overload the electrical system? One of my examples is unique. I have the optional very rare candlestick holders in front of the cluster.

Hah . I momentarily wondered the same thing when I got the car, but it was actually no big surprise to me to see this style of instrument illumination.

My previous car was an '86 Porsche 944, and its instrument cluster is lit in the same way (illuminating the gauge face from the front, not the rear) and I actually really like this, because I find the relative dimness a lot easier on the eyes during extended night driving. Somehow it 'feels' less fatiguing to me, than bright backlit systems.

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1984 300D Turbo, 326000 Km, Thistle Green Metallic

You had me going for a split second when you said you liked it. Then I thought. You are not at rock bottom yet. As the car ages and builds miles the lighting channels continue to deteriorate. Bulbs darken etc. You have a relatively low miles example.
I am sure of this as you can still see the instruments at night . Really though the concept as you mention is good.
I also tried reading the lumens with my meter. The meter had never failed me before. Even during a total eclipse.

120MPH on the autobahn, between cities, at night, with a new moon? Yeah, I can see you might not want the dash lights too bright. But in the city with streetlights and a full moon, probably want them a bit brighter. Seems they designed for the one case but not the other. Probably had to with lots of late night road testing the engineering staff was up to or something

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'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png

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