1987 Mercedes Benz 420SEL

Formerly one of the most basic circuits in the vehicle, the headlights have automatic dimming light-sensing switch to automatically turn them on, and auxiliary driving lights integrated into them.Keep in mind that these items have their own controllers and relays that operate them.Always turn to your DMM and wiring diagrams to isolate problems.
The dimmer switch in older application is connected in series between the switch and the headlamps.When curent is turned on the dimmer switch directs the curent to the selected bulb.
checking that dimmer swicth may help you find the answer of your question.

I would believe that could work, but this vehicle has no automatic headlight dimmer. It's done with the signal lever. It must be something else. What's unusual is that it's only the passenger side that goes out.

[quote:6e5484e5f9="mathiaso"]Formerly one of the most basic circuits in the vehicle, the headlights have automatic dimming light-sensing switch to automatically turn them on, and auxiliary driving lights integrated into them.Keep in mind that these items have their own controllers and relays that operate them.Always turn to your DMM and wiring diagrams to isolate problems.
The dimmer switch in older application is connected in series between the switch and the headlamps.When curent is turned on the dimmer switch directs the curent to the selected bulb.
checking that dimmer swicth may help you find the answer of your question.[/quote:6e5484e5f9]

The dimmer switch in older application is connected in series between the switch
(the signal lever ) and the headlamps.When curent is turned on the dimmer switch directs the curent to the selected bulb.
checking that dimmer swicth may help you find the answer of your question.
you need a wiring diagram and a DMM.