Almost all the interior lights on my 1990 300E don't work. One day (about 2 months ago) I turned on the headlamps and none of the interior lights went on.

I checked the fuses and they seem fine. I also tried fiddling with the knob that dims the dash.

THE following DO NOT light on:

The dash lights (speedometer, tach, and other guages), all the front vents, all the climate control buttons, the radio lights, the window switches by the shifter, (the shifter light burned out 2 years ago, so I don't know about that one, but I suspect that would be out too), and the rear window switches, the sunroof switch, and the headlight switch lights.

The following interior lights DO go on:

the Front dome (when you open the door and when you turn it on manually), the rear light for the back seats , the lights in the bottom of all 4 doors when you open them, the vanity mirror lights for both the passenger and driver, and the glove box light.

Note: when you start the car, all the warning lights come on (ie, SRS, washer light, oil light, check engine light etc.).

What could it be? Any suggestions? I'm tired of driving in the dark, and feels like I'm driving a clunker. I don't really feel like going to MB and paying $200 - $300+ which is money I really can't afford to give (and which I did too much in the past). thanks in advance.

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'90 300E
Lowered with Eibach Springs
Mouldings and bumpers painted body color
Clear front corners
94/95 W124 Taillights

Could be your headlight switch. The kick panel below the headlight switch is easy to remove and the headlight knob pulls off and the switch is held in with a nut around the threaded shaft of the switch. If you can get a wiring diagram and "hot wire the panel lights to check if the problem is inside the headlight switch.

i would bet that its your rheostat (dimmer switch) This supplies voltage to all of the interior lights that you describe NOT working. The very same thing happened to me (lights out) and when i touched the dimmer switch, all the lights came back on. The dimmer switch is relatively easy to replace, it only requires pulling the insturment cluster. It is also relatively cheap... $31 at the fastlane.

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Daily Driver: 02 E430 4MATIC
In the family: '03 E500 // '04 ML500 // 64 220SE

You may find that the fuse located on the back of your instrumnet cluster is the source of this problem. It is red in color and it looks similar to a bulb, let me know if you have difficulties getting a part number.

sounds like its the red fuse in the cluster to me...
search up my postings, i had this same problem.

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87' 300E champagne - Euro headlights and corners, 8-hole rims, 140,000miles/220,00km.

this reminds me of what happened to me. the lights slowly started to dim, while the rheostat was turned all the way to the right. i took it to my mechanic and he found out that it was a short in the cruise control which caused all the lights ( exactly the same as your description ) he disconnected the cruise control and replaced the fuse for the interior lights and then all worked well. good luck getting it fixed.

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Car which i own - 1987 Mercedes Benz 300e shown here http://www.cardomain.com/memberpage/790052