how can I dim/turn off the headlights when the ignition is on? on 2007 Dodge Sprinter 3500

to signal other drivers at night it is usefull to be able to turn the headlights off momentarily, and gate guards appreciate the courtesy when driving onto a military facility. I thought the easiest way would be a dimmer switch under my left foot but I can't seem to isolate (find) the wire. The fuse marked headlights located on the steering column does NOT turn the lights off when pulled. I've tried to find a wiring diagram for my Winnebago View/Sprinter but haven't found a source. Thanks ,Gordon

Asked by for the 2007 Dodge Sprinter 3500
Probably not going to be able to tap into the wiring, but you can have fog lights installed with a toggle and switch them on and off to signal.
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we put a toggle hard wire at the head light bulb, no lights during the day , or if van is running at a truck stop, if you turn the lights on you can use the fog lights in rain.