I assume this is on your 92 300E. Check the fuses, Mercedes is real good about sharing fuses. Each headlight low beam on it's own circut, High beams on their own, with the right high sharing the indicator light, tail lights on separate circuts too. On mine the right tail light shares the circut (fuse #7) with right parking light, license plate light and dash lights.

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Mike Tangas
73 280 SEL 4.5