How do you adjust the dimmer switch on a 85 190D I can't seem to find it?

Answer 1

When you say dimmer switch I assume you are refering to the internal dash-board lights dimmer switch. The dimmer switch for the dash-board lights is located on the speedometer panel.There are two black knobs that stick out between the warning lights on the dash. The right one is used to set the clock while the left one when rotated adjusts the dash-board lights and when depressed resets the odometer. This should be what you are looking for.