Mechanics

MERCEDES BENZ 420SEL

1987 All Other Makes All Other Models

Passenger side headlight goes blank when on dim. New bulbs do not help. Fuses have been checked. What could be the cause?
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Mwhit1230
January 17, 2007.




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.

Tiny
Mathiaso
Jan 17, 2007.
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.

Tiny
Mwhit1230
Jan 18, 2007.
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.
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Tiny
Mathiaso
Jan 18, 2007.

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