trying to fix electrical problem..
 

The final paragraph is most important. The rest is background, however still important.

I really don't want to pay the dealer or a mechanic just to fix a lighting problem, but I have had no success so far on my own. I posted my problem here: http://www.peachparts.com/shopforum/tech-help/187252-dash-console-lighting-problem.html but nobody seemed to know what was wrong. If you don't plan on clicking the link, here's whats going on: My dash lights stopped working, it's not the fuses, not the bulbs, not the rheostat. In addition to what I've done in that post, today I pulled out the digital multimeter. I couldn't find any broken connections where there shouldn't be any, but it didn't help that I don't really know what all the plugs that I disconnected from the instrument cluster do. If you have any knowledge on that please post. I tried using my friends Chiltons manual for up to 84 models but they are way too different to help.

What I need now is some information on the electrical system on a 95 E300D. I'm pretty sure the interior console/cluster lights are on the same circuit (or something) as the headlight warning buzzer since both do not work. I think the headlight switch opens and closes the connection to the console/cluster lights and also the buzzer. How else would the car tell when the headlights are on? Here is a list of things that may help me: schematic diagram of my models or a similar electrical system, info on what all the plugs do that connect to the cluster, accessing the wires that go from the headlight switch to the dash lights, hints/tips for finding shorts, any known repair manuals for my model. Thanks.:(

Spin fuse # 9 in it's holder, or , better yet..change it...

R&R the fuses and polish all the fusebox electrical contacts first, then R&R the potentiometer (which is repairable according to an earlier thread...search for potentiometer repair). I prefer to replace the pot with a new one since all the trouble to get to it is not worth having to do it again later.

Those things do not tolerate a moist environment that can develop due to the leaks that are apt to happen if the windshield seals are not replaced when needed or the sunroof drain chanels are not kept clear.

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I'm pretty sure it's not the fuses. I changed # 3 and 9 but it didn't change anything. Besides, all the other electrical components that go through those fuses work fine. I'm not sure about the potentiometer but there wasn't a broken connection when I tested it on the continuity tester. I tried hardwiring, that didn't work either, so it's probably not the pot. I'm beginning to think it's something to do with the light switch, because I just noticed that the fog lights and parking lights don't work either.

Parking lamps on both sides??
R/L are fused seperate, so if both are out , the L/S may be the problem
Try L/S for parking position in the Pull-Out position.
Also, on the fuses [ specially 3].. take a 12v test lamp to both sides of the fuses to verify..and do not touch the fuse ends , rather the connectors they sit in..they will fool you.
I always spin them in the holder to get a good contact

check this
 

You can have all the power you want going to the circuit but you also need a ground check you ground straps and in the circuit

Very true..and I would consider that fact for the cluster ground, but he also has no parkng lamps ..and b/c are seperately grounded, I would still suspect fuse feed or L/S

Yes, neither side is lighting up. When I put it in parking position it would not stick when i pulled the switch out. I think the fog lights can only be turned on with the L/S turned to the right. I tested the fuse connectors, and it did detect electricity running through. After changing fuses and twisting them around still nothing has changed. Good idea on checking the grounds, but I don't know which wires are supposed to be grounded.
While working on my car today, I probably turned the light switch like 20 or 30 times. After a while I noticed the headlight alarm started working again. Sometimes, the cluster lights would even turn back on, if only for a few seconds. This happens right after I turn the switch on. The alarm works relatively consistently at this point, but the dash lights don't.
I'm going to take out the light switch now. Problem is that I don't exactly know how to test for what if anything is wrong with it. Seems like maybe something is loose or barely missing a connection. Obviously I don't want to replace it just to find out that it wasn't broken in the first place. Thats all for now. I will update tomorrow. Btw, you guys have been very helpful so far, thanks.

<<I'm going to take out the light switch now. Problem is that I don't exactly know how to test for what if anything is wrong with it.>>

Light Switch [ S1] ......I show term # 5 [ gy/rd] as being 12v feed to S1 from fuse 3, and term # 4 [gy/vi] being 12v out to cluster ... That should be your test at S1 for in/out voltages w/sw ON.
Ground strap is behind cluster...

I just took out the switch. There are 11 pins and they aren't labeled 1 2 3 4 5... I can see the wires but I can't tell which pin each goes to without completely taking apart the plug. Going clockwise from 12 o'clock each pin is labeled as follows: 58R, 58L, NS, P30, NSE, 56, 57, K30, K, 31, 30, N. 12 labels but only 11 pins. I suspect that 57 might be the extra. I figured it would be easier to test for continuity in each knob position rather than voltage. I found a schematic here: http://web.mac.com/dakota/iWeb/Parts/Fuse.html
but it isn't very specific on the light switch.

K is terminal #4
K30 is terminal #5

Thanks. Just tested it, and to my suprise, the connection is not broken. I read something on an other thread about switches getting corroded on the inside, and that they just need to be cleaned, or in this case switched alot. If I wanted to take it apart it would not be easy since the metal part is bent around the plastic in 5 places. Arthur, do you know what the other pins do? I also want to test the pins that go out to the fog lights and parking lights. I'm going to plug it back in and see if the dash lights work. Be back in five.

Park/fog/etc all go from S1 to the N7 module. This is the exterior lamp monitor module.. You may ahave a bad connection there..It is in slots K at the rear of the fuse box [ relay box behind fuse box] I would unplug it and plug it back in after squirting some cleaner [ even WD ] on the plug spades..Everything branches out from there.
I will see if I can upload S1..
My scanner is kaput.

If anyone is wondering why that took longer than five minutes it's because when I went to put the cluster back in, I noticed right illumination light was missing. I gave up after an hour of searching the car. Put it in anyway, but still, no lights. Light alarm works fine now though. Now the cd player doesn't work. I turned it on and the little display says "code" with a blinking c. I thought I had put something in wrong but all the cluster plugs only fit where they are supposed to go.

Btw, it wasn't missing the whole time. I remember checking both lights in the cluster tuesday.

Cleaned the N7, and the rest of them for the hell of it. I also replaced some fuses with copper ones. They really should have came standard. Apparently the alluminum fuses on the copper causes oxidation, which I did not see. Everything works now, including the fog lights. What a pain in the ass. Somebody said those things would fool me, and I guess they did. It still might have been a corroded light switch, but who knows. I'll have to drive around for a while to make sure it's fixed. Despite the aggravation, I'm still glad I didn't go to the dealership or any other mechanic. If anyone is still listening, there are two tail lights that don't go on. I don't even know what they go to. They are the only two lights in the back that light up clear as opposed to yellow or red. If nobody knows I'll just ask the dealership when I go to get my radio code. Thanks again to everyone who offered their help.

Back-up lamps..

90% of Benz power feed problems are fuse connections....but we told you that.