My dash and console lights were not working on the '83 240D. After doing some searching I realized that it had to be the rheostat located on the back of the instrument panel. If you own an older MB and none of your dash or console light are working, there's a good chance your rheostat is corroded. What is a rheostat you say? A rheostat is simply a device that allows you to control the resistance in a circuit. In this case, it allows you to control the brightness of the dash lights. Unfortunately, the internal contacts tend to corrode over time and eventually enough corrosion will halt the current flow through the rheostat with the end result being no more lights.

The most common "fix" for a bum rheostat is to simply solder a jumper wire across the two metal strips on the back of the rheostat. This effectively bypasses the internal components, which is good because it gets your lights back. However, in doing so you sacrifice the ability to dim your lights if you want to. The argument for bypassing the rheostat is that, even on "high", the dash lights in these older MB cars are not all that bright. After fixing mine, I agree, but nevertheless, I still wanted to open up the rheostat to see what it looked like inside and, once I did, I realized it wouldn't be a hard fix - so I cleaned up the contacts, put it back together and now it works great. What follows is a DIY on refurbing you dash light rheostat.

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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
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"Back off, man. I’m a scientist” ~ Peter Venkman